Please excuse me for very bad english.

6770 sometimes stops crunching, but keep the gpu busy at 0%.
Screenshot: http://imageshack.us/a/img222/7231/boincf.jpg

Usually it takes 5-7 minutes, and now is over 40. Videocard is not overclocked.

Windows xp (sp 3)
Catalyst 12.1 - it's the last one with opencl support for windows xp. App sdk is only for vista/7.

By the way, boinc thinks that is 5700, but i'm sure it's 6770. )

Starting BOINC client version 7.0.31 for windows_intelx86
Processor: 4 AuthenticAMD AMD Athlon(tm) II X4 605e Processor [Family 16 Model 5 Stepping 2]
OS: Microsoft Windows XP: Home x86 Edition, Service Pack 3, (05.01.2600.00)
Memory: 3.25 GB physical, 5.09 GB virtual
Disk: 878.91 GB total, 547.90 GB free
ATI GPU 0: ATI Radeon HD 5700 series (Juniper) (CAL version 1.4.1664, 1024MB, 996MB available, 2480 GFLOPS peak)
OpenCL: ATI GPU 0: ATI Radeon HD 5700 series (Juniper) (driver version CAL 1.4.1664, device version OpenCL 1.1 AMD-APP (851.4), 1024MB, 996MB available)