Hitachi tv random crashes

Hi,

I've got an hitachi tv model number l22dp04u a, and ive got an issue with that i cant seem to constantly replicate.

The TV will turn on a work as normal until a after a random period of time it will make the speakers pop then either a set of green and purple or 2 shades of grey lines will appear on the screen.

Unplugging the tv and and leaving it for a few seconds returns it to normal until it does it again after a random amount of time.

It seems to be worse once the TV gets warm but im struggling to get any ideas of what is going on, i have googled the issue but can't seem to find anything similar to the symptoms.

Anyone have any idea if its likely to be a main board or a psu board issue.

Regards

Ian