Hi Shannon,
I have implemented a fix for the problem. It doesn't allow 'u' to work when you are debugging (this seems to be a VS2008/VB.NET/ASP.NET limitation I can't work around), but it prevents the freeze. You can test it by downloading the following DLL on top of your current one (probably installed in its default location, "C:\Program Files\ViEmu", unless you chose another directory on install):
http://www.viemu.com/track/u1/ViEmu.dll
Make sure all VS sessions are closed when writing over the file. You can check that the new DLL is installed by typing :ver, which should show '2.1.25.undo'.
After this, 'u' should never freeze, but it won't do anything at all if you are debugging a project.
Let me know if this indeed works as described, and I will build & release ViEmu/VS 2.1.26 with this fix.
Thanks,
- Jon
PS: BTW, checking the Tools|Options|ViEmu checkbox "Prevent VS2005 warning "cannot edit while running"" setting should make Undo work in this case, but it doesn't, for some undocumented reason. If you enable it, though, the toolbar buttons to undo, and ViEmu's 'redo', will indeed work. I tried to tweak it to get 'undo' to work, but there doesn't seem to be any way.