I found a solution...
First off, I don't think I was very clear in last post, so let me clarify
the problem I was having, so the solution may make more sense.
1) Received a task item via pop3 email
2) Accepted it, went into tasks folder
3) backed up PST file, re-installed vista & outlook
4) Created new personal folders, copied ONLY e-mail/contacts/calendar (not
tasks!)
5) Created another set of personal folders for general storage, made it the
default set (each e-mail account goes into a seperate set of folders)
6) Clicked on old task request e-mail, gave me error and was unable to
read/delete e-mail message because of mentioned error
To fix:
1) Go to tools -> accounts -> data files, make the personal folders that
contain the task items you can't open the default folders
2) Restart outlook
3) Delete task items
4) Go to tools -> accounts -> data files, make your original default folders
default again
5) Restart outlook
Done.
Only issue I see with this is when I made my folder set for gmail default,
outlook added a bunch of crap I didn't want to it, such as journal, contacts,
etc., and now I can't delete those sub-folders. It would be nice if someone
from Microsoft looked into this, the main bugs I see in this expirience are:
1) When copying e-mail items from one PST file to another, if it's a task
request and you didn't copy the corresponding task item, you will get this
error any time you try to read/accept/decline/delete the task request e-mail
in that folder's inbox. If a task request in your inbox can't find it's
associated task item, perhaps outlook should treat it as a new task request
and form a new association... Or ignore the item completely if it's just a
status update to a task it can't find.
2) When setting a folder as default, many sub-folders get automatically
created such as Calendar, Tasks, Contacts, Journal, etc. Those folders are
not delete-able even after the PST containing those folders is not the
default folders anymore. Since I want to syncronize only one out of 5 e-mail
accounts with another copy of outlook on another computer, I need at least
this one e-mail account in its own PST file, but I don't want these
contact/calendar/task folders as they don't contain anything (a different PST
file has those folders with the information I want), and I don't want them
confusing my PocketPC when syncronizing with either computer.