Vista - system settings not saving

I have Vista Home Basic on my laptop, which, aside from somewhat slow lately, has been running fine. Within the last month or two i purchased a second monitor, hooked it up, and it worked perfectly, i had the screen extended to the right. Then, for reasons involving the amount of space on my desk, I moved the external monitor to the left and changed the configuration for it, which again, worked fine up until yesterday. Now, whenever i turn my laptop on, or close it, then open it again later the old settings come back, and the screen is configured for the right instead of the left, so now, every time i start up my laptop, i have to change the external monitor's settings back to the left, and i can't figure out why the settings aren't saving. and suggestions?

Thanks in advance,

Chris_