Slitherine

I have been playing FoG with no problems for several months.
Two seperate occasions and two seperate games tonight I have had a computer freeze.
No response, no ability to switch back to desk top and no closing through Ctrl Alt Del.
In both instances I had to power down. Both instances were within 30 minutes of each other around 8.00pm GMT.

Was there any server issue or do I need to look to my rig/network connections/isp provider?

The network would be an unlikely cause of this type of issue - it is probably some sort of lockup in the graphics card/3D part of the game. I'd guess you overheated? What are your system specs?