LG Android – no response from the phone – Backup failed

Today, trying to backup Contacts and Calendar for my Android phone – LG P500 Optimus using LG PC Suite IV, I received the following error:
No response from the phone - Backup failed

Tried some more, tried unplug USB, etc., still no luck.

After playing a while, I noticed, that backup process / progress indicator stops right after phone screen turns off into sleep mode. So, I tried to go to Settings – Display – Screen timeout – 30 minutes. That fixed backup problem.