Hy,
until now I never had any probs with GPU, but since today I´m unable to upload my WU:
heres the BOINC log:

08.03.2009 18:13:00|GPUGRID|Sending scheduler request: Requested by user. Requesting 0 seconds of work, reporting 1 completed tasks
08.03.2009 18:13:10|GPUGRID|Scheduler request failed: HTTP file not found
08.03.2009 18:14:10|GPUGRID|Fetching scheduler list
08.03.2009 18:14:16|GPUGRID|Master file download succeeded
08.03.2009 18:14:21|GPUGRID|Sending scheduler request: Requested by user. Requesting 0 seconds of work, reporting 1 completed tasks
08.03.2009 18:14:31|GPUGRID|Scheduler request failed: HTTP file not found


I´m running a Intel Core 2 duo T9300 (2x 2.50 Ghz)
4GB Ram
2x Geforce 8800 GTX (but its a Notebook so BOINC only find one CUDA device , without SLI-mode on, too)
And I´m using a VISTA 32bit

maybe someone can help me with it

I have had similar issues for me the fix was simple i stopped boinc and reboot my machine.
But i have seen this also with s@h that when i upload was done 100% but the confirmation failed from the server report.
After 60 tries i broke it off and lost the unit rewards

reboot don´t work,
I try detach and reattach to the projekt, but it´s still the same error:

08.03.2009 21:23:38|GPUGRID|Sending scheduler request: Requested by user. Requesting 0 seconds of work, reporting 1 completed tasks
08.03.2009 21:23:48|GPUGRID|Scheduler request failed: HTTP file not found
08.03.2009 21:24:49|GPUGRID|Sending scheduler request: Requested by user. Requesting 0 seconds of work, reporting 1 completed tasks
08.03.2009 21:24:53||Removing account manager info
08.03.2009 21:24:57|GPUGRID|Resetting project
08.03.2009 21:24:57|GPUGRID|Detaching from project

08.03.2009 21:25:35||Attaching to http://www.gpugrid.net/
08.03.2009 21:25:45|http://www.gpugrid.net/|Master file download succeeded
08.03.2009 21:25:50|http://www.gpugrid.net/|Sending scheduler request: Project initialization. Requesting 1 seconds of work, reporting 0 completed tasks
08.03.2009 21:26:00|http://www.gpugrid.net/|Scheduler request failed: HTTP file not found
08.03.2009 21:26:35|http://www.gpugrid.net/|Sending scheduler request: Requested by user. Requesting 31474 seconds of work, reporting 0 completed tasks
08.03.2009 21:26:45|http://www.gpugrid.net/|Scheduler request failed: HTTP file not found

Try to detach from the project then close down boinc, then check the map where the projects are and see if the map is still there.
If so delete this map by hand and then start boinc again and reattach to the project.

after detaching there´s no gpu map left..
and after restart BOINC and reattach to GPUGrid the problem is still the same

Log:
09.03.2009 00:08:34|http://www.gpugrid.net/|Master file download succeeded
09.03.2009 00:08:39|http://www.gpugrid.net/|Sending scheduler request: Project initialization. Requesting 1 seconds of work, reporting 0 completed tasks
09.03.2009 00:08:49|http://www.gpugrid.net/|Scheduler request failed: HTTP file not found

Problem solved, after complete uninstall, reboot and reinstall BOINC now GPUGrid runs like it used to be.