I use FireFox as my Browser and have a 3G account with TrueMove H as my service provider. A few days ago most all sites I tried to visit, including ThaiVisa, have been hijacked with the message:-

We're redirect you to hlife.truecorp.co.th/recommend_ppu_block?url=www.thaivisa.com
If you are not automatically redirected. click

This site pops up. I have to try many times to get to the site I want.

hlife.truecorp.co.th/register_prepay/alert

Clearing cookies (CCleaner) fixes the problem for the remainder of the session but when I reboot and open FF the crap starts again.
Tried several types of "add on" site blockers without much success, They just mess things around.
Any suggestions?

Thank you.

The 2nd link you posted goes to a page telling you to register your sim card. Your problem may go away when you do the registration.

I have true move on my phone and started getting a long message to do the registration every time I made call. Did the registration and no more message.

Thank you Mr Joe, on the ball as ever.

Registered our Phone Sims but didn't give the Sim, hidden in a dongle under the dest amongst the spagette jungle, a thought.

Now registered and the problem appears to be solved.

If you use a prepaid True Move 3G, check if your credit is still sufficient...