Can you restart and then post your message log ?
Cheers

Do what you're requested to do.....

It might actually help

Hit the Ctrl+Shift+E keys simultaneous. That brings up the event log. Copy the whole and paste it in a reply. Till then we're pretty clueless why that message is repeated, which can be up to 24 hours.

2/19/2016 10:56:36 AM | | Starting BOINC client version 7.2.47 for windows_x86_64
2/19/2016 10:56:36 AM | | log flags: file_xfer, sched_ops, task
2/19/2016 10:56:36 AM | | Libraries: libcurl/7.25.0 OpenSSL/1.0.1 zlib/1.2.6
2/19/2016 10:56:36 AM | | Data directory: C:\ProgramData\BOINC
2/19/2016 10:56:36 AM | | Running under account Cmdwings
2/19/2016 10:56:36 AM | | No usable GPUs found
2/19/2016 10:56:36 AM | | Host name: user-PC
2/19/2016 10:56:36 AM | | Processor: 4 GenuineIntel Intel(R) Core(TM)2 Quad CPU Q8400 @ 2.66GHz [Family 6 Model 23 Stepping 10]
2/19/2016 10:56:36 AM | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss htt tm pni ssse3 cx16 sse4_1 nx lm vmx tm2 pbe
2/19/2016 10:56:36 AM | | OS: Microsoft Windows 8.1: Professional x64 Edition, (06.03.9600.00)
2/19/2016 10:56:36 AM | | Memory: 3.84 GB physical, 7.71 GB virtual
2/19/2016 10:56:36 AM | | Disk: 465.22 GB total, 436.46 GB free
2/19/2016 10:56:36 AM | | Local time is UTC -7 hours
2/19/2016 10:56:36 AM | World Community Grid | URL http://www.worldcommunitygrid.org/; Computer ID 3446872; resource share 100
2/19/2016 10:56:36 AM | World Community Grid | General prefs: from World Community Grid (last modified 17-Nov-2015 22:32:39)
2/19/2016 10:56:36 AM | World Community Grid | Computer location: home
2/19/2016 10:56:36 AM | | General prefs: using separate prefs for home
2/19/2016 10:56:36 AM | | Reading preferences override file
2/19/2016 10:56:36 AM | | Preferences:
2/19/2016 10:56:36 AM | | max memory usage when active: 3931.61MB
2/19/2016 10:56:36 AM | | max memory usage when idle: 3931.61MB
2/19/2016 10:56:36 AM | | max disk usage: 20.00GB
2/19/2016 10:56:36 AM | | (to change preferences, visit a project web site or select Preferences in the Manager)
2/19/2016 10:56:36 AM | | Not using a proxy
2/19/2016 10:56:37 AM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 10:56:37 AM | World Community Grid | Requesting new tasks for CPU
2/19/2016 10:56:39 AM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 10:56:39 AM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 1:12:59 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 1:12:59 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 1:13:01 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 1:13:01 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 2:26:53 PM | | Fetching configuration file from http://boinc.unex.es/extremadurathome/get_project_config.php
2/19/2016 2:27:16 PM | | Project communication failed: attempting access to reference site
2/19/2016 2:27:18 PM | | Internet access OK - project servers may be temporarily down.
2/19/2016 4:24:52 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:24:52 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:24:54 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:24:54 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 4:26:29 PM | World Community Grid | Fetching scheduler list
2/19/2016 4:26:31 PM | World Community Grid | Master file download succeeded
2/19/2016 4:26:36 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:26:36 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:26:38 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:26:38 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 4:28:24 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:28:24 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:28:26 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:28:26 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 4:31:47 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:31:47 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:31:49 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:31:49 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 4:39:11 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:39:11 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:39:14 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:39:14 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 4:52:12 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 4:52:12 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 4:52:14 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 4:52:14 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 5:20:52 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 5:20:52 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 5:20:54 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 5:20:54 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 6:24:52 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 6:24:52 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 6:24:54 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 6:24:54 PM | World Community Grid | [error] No close tag in scheduler reply
2/19/2016 8:31:07 PM | World Community Grid | Sending scheduler request: Requested by project.
2/19/2016 8:31:07 PM | World Community Grid | Requesting new tasks for CPU
2/19/2016 8:31:09 PM | World Community Grid | [error] Can't parse task in scheduler reply: unexpected XML tag or syntax
2/19/2016 8:31:09 PM | World Community Grid | [error] No close tag in scheduler reply

NOTHING to do with the problem of the OP. Search for threads discussing the Peer cert problem... Debian Jessie has an issue [bug], where it is not able to find the proper certificate. Workaround is offered in those Peer Cert. threads. Specifically there's a post on the matter in the Community maintained FAQ's forum.