Try renaming or deleting C:\Program Files\EQ Item Collector\itemcol.db file. The error is usually a corruption in the file. Uninstalling item collector does not remove this file (unless you have some special clean up / file removal utility that's not standard with Windows).
Hopefully this helps, and has always corrected the problem when it wasn't a problem with item collector itself (usually right after patches and only for a few days to a week or two).
nevermind, it's borked again. I hadn't verified it for a week or two, but during Fabled it was borked, then it worked, now not again. :(
Yther Ore.
Edited, Jun 30th 2009 1:27am by Yther