igo 8.3.5 freezing after 20mins or so

Hey guys new to this but do know a few things about computers and files what not.
Had a question I have a chinese Double din gps in my winter car and it seems to be freezing after about 20mins or so. Now I have seen here and there that u could alter the sys. file on the sd card so the gps uses less memory and runs more stable, just need to know how exactly how it's done.
Or do you think the unit is over heating causing the screen to sometimes go purple or green or sometimes just stop responding all together.

Any help would be greatly appreciated.
And sorry if this is posted somewhere else I'm new to the fourm and can't located a post with my issue.

Thanks again.

Do any of the other programs on the double din stop working?
What is the memory of the unit?
Try renaming the speedcam directory so its not seen on start up and see if it still freezes. (memory) same with Dem files.
Sys.txt can be changed to help mem issues but I would expect the unit to of been set up to run ok.

Bazzle

While it's true that it can be a device malfunction, my experience is shutdowns and/or error messages can also be attributed to too much content trying to load and be used. Have you considered deleting the .dem files, building files, reducing the speedcam area, reducing the number of maps to your geographical area, etc.?

Bazzle has good questions in #2. I'm looking forward to the answers from you.