Some database on your machine must be corrupt. Because it is occuring as soon as you open Notes, I’m guessing it is your address book (names.nsf). It could also be the file that defines the workspace (desktop6.ndk).
Try these steps.
First, find your Lotus Notes Data directory. Find the file desktop6.ndk. Change its name to desktop6.old.
Then, delete cache.ndk.
Now start Notes. A new desktop6.ndk will be created with no workspace icons. You will have to re-add them (your mail database and anything else you use).
If that doesn’t work, find the bookmark.nsf database and delete it.
If that doesn’t work, open a command window (Start > Run > cmd > OK). Change Directory (CD) to your Notes application folder, (e.g. CD C:\Lotus\Notes). Type these commands, one after the next. Let each run to completion before trying the next one.
ncompact -c -i -d
If that doesn’t work, it may be your notes ID file. Request a new one from backup from your adminstrative team.
Hope something here does the trick.