^^^
If you suspect this is a software related issue, then try and find or borrow an external TV tuner card from a friend of yours, in that case you can be sure whether its a Computer software related issue or a motherboard issue or a hardware issue with the monitor it self..
Good news is if its a monitor related issue, then ask for HCL support in case of warranty still valid or any local TV repar guy would be able to fix these CRTs with nominal charges (Rs. 250 or 300 at max)