This has been a long standing bug with the Windows version of 1Password, but I've always worked around it by using Firefox/Chrome instead. Not every time, but often (a few times a day), Internet Explorer will crash when I hit the ctrl+\ shortcut to unlock 1Password. All tabs are recovered fine, and I can then hit the shortcut again to unlock 1Password and log in.
The most recent time I noticed this crash, I believe 1Password was already unlocked, and I was then browsing to another site to fill a login. After IE crashed, I then had to unlock 1Password again and it worked fine.
I've seen this issue across multiple computers running Windows 7 and Windows 8. Both IE9 and IE10 are affected, not sure about IE8. Let me know if there are any logs I should be looking at that might shed some light on the problem.