Regarding OFO:
The Hotfix changes the way BE/OFO uses memory. After the fix, it will use contiguous uniform blocks of memory.
Best way to setup OFO: put an 8Gb IDE harddrive in your server where you get this error. Do not put any data on this drive. Configure the OFO Wizard to point to that drive for the OFO static volume location. You will never get another OFO error.
If you cannot do that, you should never specify a location for OFO static volume other than the default unless you are specifying a volume/drive that you never backup.
OFO in 8.6 will change the location of the static volume dynamically: ex. your server has C: D: and E: drives. When it backs up C: it will place the static file on D:; when it backs up D: it will place OFO file on E:; when it backs up E: it will place it on D:.
Only caveat to above is if you have one logical volume on a drive. Say your server only has a C: drive and no other volumes or harddrives. In this situation, the static volume will not increment or grow past the initial size setting of the OFO static volume. Therefore the only thing you can tweak is the initial setting. So if this is the situation for the error you are getting, you need to find out how much data is backed up on C:; how much free space do you have. Say you are backing up 20 Gb and have 6Gb free. Then you would set the OFO static volume initial size to 400 Mb and max doesn't matter since it cannot increment.
As for your question about Exchange files skipped. OFO cannot backup transactional databases (SQL, Exchange, Oracle). The only way you can backup the files where Exchange is installed is to stop all the Exchange services and do a flat-file backup. If you are using the Exchange agent to backup the databases/logs while Exchange services are running, YOU DO NOT NEED TO BACKUP THE DIRECTORIES WHERE EXCHANGE FILES ARE INSTALLED!
Veritas wrote their own OFO for Backup Exec 9.0. They no longer use OTM (Open Transaction Manager) which will eliminate a lot of these stupid errors.
Enjoy!