Registry cleaners can cause problems just like this - don't use them anymore.
Here's an article explaining why: http://www.windowsbbs.com/showthread.php?t=61015
FYI - the article was written for XP, but it also applies to Vista/Win7
If it doesn't crash in Safe Mode, then (as you've surmised) it must be something that loads in normal mode and not in Safe Mode. I'd suggest using this free tool to see what loads with explorer.exe (a lot of stuff!): http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx
Most commonly this is caused by shell extensions - so here's a freeware tool for viewing them also: http://www.nirsoft.net/utils/shexview.html
If nothing shouts at you, it'll probably be a matter of disabling 5 to 10 and testing, then another 5 to 10 and testing, etc
Good luck!
Here's an article explaining why: http://www.windowsbbs.com/showthread.php?t=61015
FYI - the article was written for XP, but it also applies to Vista/Win7
If it doesn't crash in Safe Mode, then (as you've surmised) it must be something that loads in normal mode and not in Safe Mode. I'd suggest using this free tool to see what loads with explorer.exe (a lot of stuff!): http://technet.microsoft.com/en-us/sysinternals/bb963902.aspx
Most commonly this is caused by shell extensions - so here's a freeware tool for viewing them also: http://www.nirsoft.net/utils/shexview.html
If nothing shouts at you, it'll probably be a matter of disabling 5 to 10 and testing, then another 5 to 10 and testing, etc
Good luck!