Outlook looking for backup file on startup

[htown]

I have never had this problem before and I am not sure what the hell I did but now whenever I start Outlook, it tells me

"The path specified for the file L:Backups/Outlook/Outlook Backup.pst is not valid"

I am not even sure why it is looking for this. I have an external drive that is USB 20 that I only plug in when i back up stuff because it tends to slow things down. For some reason, Outlook is looking to this drive when it starts up. I have BACKUP installed and I have check it but the backups do not even go to that drive. Why in the heck is it looking to this drive and more importantly, how do I stop it?

Many thanks,
Houston