Hi Artur,
As per the CUVA troubleshooting guide you need to collect logs from PC to find the cause of this issue:
Capturing Logs Automatically When the Applications Crashes
If Cisco Unified Video Advantage unexpectedly crashes, the Problem Reporting Tool automatically collects installation, application, and client computer system information to automate the trace and crash-dump collection process on the client computer.
Procedure
Step 1 Tell users to follow the user guide instructions for capturing log files:
•Locate the automatically generated Zip file on their desktop.
•Send the Zip file from their desktop to you through e-mail.
If you set up an e-mail support alias at the time the application was deployed or installed, the file is automatically sent there. For details, see the "Related Topics."
Step 2 Provide the Zip file to the TAC representative, if requested.
http://www.cisco.com/c/en/us/td/docs/video/cuva/2_1/english/installation/guide/book_wrapper/vtrble.html#wp1052969
HTH
Manish