USB harddrive all of a sudden stops being able to be recognised

Hi, i had a few problems with my computer so took it to a man to fix. He fixed it fine. few days later I unplug my Seagate Free Agent 1tb harddrive like i've done a million times, go to plug it in later and it is not recognised by the computer (ie cannot be seen in my computer, disk management and device manager) But the little safely remove hardware thing is there in the task bar? I tried using that to stop the device but that didnt work.
Thankfully though once I restart my computer it appears again. which leads me to think that the computer has some sort of autorun problem?

HD works on other computers as per normal. Other usb devices work fine on the computer.

I have not taken it back to the man because It could very well be something i've done and not willing to pay another 200 bucks for him to tell me that.

I am running vista home premium 32bit on acer aspire 5536 laptop, amd dual core 2.10 ghz, 3 gig ram.

any help much appreciated

Hello doofy55,

Welcome to Vista Forums.

Do you have the installation disks for Window Vista?

Thanks for the quick reply.
No the disk didn't come with the laptop when i bought it.