SharePoint Foundation Search security credential failed at the test

[lampar]

I have Backup Exec 2012 and SharePoint 2010.
The backup was up and running for about an one year.
Soddenly it starts failed with following errors

Backup- SharePoint - 80\Content-DB 1 (XXXSQL\WSS_Content_XXXX)
V-79-57344-65300 - The SharePoint resource is not responding. Backup set canceled.

V-79-57344-33861 - The media operation was terminated by the user.

V-79-57344-65072 - An error occurred while connecting to the Backup Exec Remote Agent on the Backup Exec server. Ensure that the job options are correct, and then submit the job again. The backup set was not created.

After this job is failed, none of my other jobs can connect their services.
Have to reboot server, put this job on hold and only after that I can finish other jobs.

I test credentials on job and realised that the it failed for the SharePoint foundation Search (rest of the services credentials are fine)
The same credentials I’m using for all my backups before and now and have no problem with them.

I tried to change it for sql admin, farm admin, sp admin

No luck,  all failed.
No recent changes or upgrade were done on SharePoint, SQL or backup Exec servers.

What could be a problem,

Please advise

[VJware]

After this job is failed, none of my other jobs can connect their services.

Would you pls confirm if there was an application crash event logged in the event viewer ? Or does any Backup Exec service stop automatically ?

And, here are the permission requirements for Sharepoint 2010 ~ http://www.symantec.com/business/support/index?page=content&id=TECH157059

[lampar]

services stoped followed after the

Event 34113

Backup Exec Alert: Job Failed

(Server: "EXCALIBUR") (Job: "Server Farm 2010 -Full") Server Farm 2010 -Full -- The job failed with the following error: A communications failure has occurred with a Sharepoint resource.

Ebvent 1000

Faulting application beremote.exe, version 14.0.1798.0, time stamp 0x4f1e02d7, faulting module ntdll.dll, version 6.0.6001.18538, time stamp 0x4cb73957, exception code 0xc0000374, fault offset 0x00000000000a7857, process id 0xa58, application start time 0x01ce55cf30f7251d.

and Event 258

Process beremote.exe requested memory dump but the maximum number of memory dumps has already been reached.

[VJware]

Browse to \Program Files\Symantec\Backup Exec\BEDBG directory & clear the contents.

Ensure the media server & remote agents on all sharepoint servers are fully updated. If they are updated & issue still occurs, would recommend to log a formal support case for us to review the crash.