Hi Miłosz Cechnicki,
Thank you for your report. We are aware of this problem, it is caused by our virtualization. It is already fixed and the fix will be available in the next internal build.
Sorry for the caused inconvenience.
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items.