I was having issues with SETI@home last night and this morning. I have it set up to start in screensaved mode. It kept trying to start up and quickly shut down, leaving a row of little green icons in my tray. I tried starting it up in standalone mode and got an error numbered 100. Here’s the fix from the site:
If you are unable to connect due to “100” errors (or perhaps “41”) you may need to exit SETI@home, remove the files “result.sah” and “user_info.sah” from your system, and then restart SETI@home. This is probably fallout from the user database crash a few days ago. Sorry for the inconvenience.
That should do it, it worked for me.