Well, for me 6.5.3 is freezing just like 6.5.
What I have done so far at the recommendation from Symantec is:
1. Run the PartInNT utility in the following folder:
C:\Program Files\Symantec\Backup Exec System Recovery\Utility
And verify there are no errors identified for your drives. I have 1 Dell 2800 server where the RAID manager says all is fine, but the PartInNT shows errors. Symantec is claiming that is the problem.
2. Uninstall any Anti-Virus software and SBESR, then install only SBESR. I have Symantec AV and Symantec told me they are aware of issues with SBESR and their own AV... Wow...
I uninstalled them both, rebooted, and am still having the same problem on the server with the drive errors (as identified by PartInNT).
On other servers (I have 9 and I am having this problem on several, but intermittently) I have no PartInNT errors identified, but SBESR 6.5.3 still locks up unless I reboot. After the reboot the backups works. I have not jotted down how many times they work tho.
Symantec support says my issue is "being advanced to our Level 2 technical support team"