Steps to reproduce:

1. Changes in configuration...
   None.
2. Navigate to screen title...
   Latest Data
3. Click on screen element...
   <some host>
4. ...

We monitor over 200 hosts and there is only one that persists with this issue. Latest Data reveals disks that have "No Data Available". Graphs reveal spotty access. Successful drives are indicated by "0 C:...", etc. but failing drives are "1: ..." (without a drive letter). I suspect Backup Exec is making temporary VHD disks but I don't have a good reason for saying so, just my gut. This has been reported to Zabbix forum with no responses:

https://www.zabbix.com/forum/zabbix-help/476767-disk-discovery-discovers-non-existent-disks

The above link has screenshots and log file.

Result:
See screenshot...
See log file...
See memory dump...
Expected:
See screenshot....
See attached patch file...