windows 8 – Bitdefender’s vsserv.exe blocking IO? (on WIN8)

Since yesterday, I am experiencing slow responses to I/O-heavy operations. When looking at CPU, memory, etc. I saw a cycle of roughly a minute when the computer seems to be blocked, then a minute of regular activity, then again a minute blocked.

“Blocked” means that there seems to be no I/O activity on any of the drives (3 physical ones, 5 logical, plus 1 veracrypt which is not shown in resource monitor). Resource Monitor shows the throughput and queue length to fall to 0 (sic!) for a minute, although a program actually is waiting for I/O. After the minute, activity is resumed.

The device list (“Datenträger” in German) of the resource monitor shows literally hundreds of vsserv.exe calls (distributed across a handful of vsserv.exe PIDs), most of them writing to a file ecal.db-journal in the BD program directory. The file seems to be created and deleted permanently, as the file explorer shows this file to exist or not exist while showing the directory’s content. When activity resumes at the end of the minute, these vsserv.exe entries go away, and the device list contains only a handful entries, which are quickly filled again by vsserve.exe entries.

The pattern does not seem to be related to actual I/O requests, it’s visible whether or not a program requests I/O. It’s independent of whether the computer is connected to the internet. The Bitdefender UI is affected as well (no response during a blocked phase).

When left alone (no user interaction), the Bitdefender UI oscillates between “Your Device is at risk” (I turned off protection) and “Services not responding” (as though it did not have internet connection, although the laptop is connected), in a rythm slightly offset from the block/unblock phases.

I am running Windows 8.1 on an Acer laptop, with Bitdefender Antivirus Free (engine 7.88599).

Any ideas?

EDIT: After finishing this question, I wanted to turn BD protection on again, but got “Failed to activate. Please retry”…