Thanks for the help Berb. i changed my gfx card settings and also installed a game booster and it has sorted the problem. I loaded the save and instead of getting a slide show of 1 and 2 fps it is performing like it was when i started the campaign. After 4 years of this happening i can finally get to sink some ships of my home town in the northeast uk.
Thanks again Berb you are a star and a true hero of this forum