GetResourceStream access violation exception

I have this line of the code in my app. I use it to extract some .xaml resource from other class library:

Application.GetResourceStream(new Uri("DomRes;component/Resources/" + sketchlink + ".xaml", UriKind.Relative))

Most of the time it works just fine, but sometimes it throws this strange exception:

Exception thrown at 0x7780E466 (ntdll.dll) in Dom.exe: 0xC0000005: Access violation reading location 0x6DD371F4.

I can't figure out why. I call this line of code several times, and it fails only after certain number of repetitions.