iPhone won't connect to computer but will charge

Any advice on this would be so appreciated please as I've been trying out everything for the past 24 hours, and nothing has worked!

I have an iPhone 4s, everything is up to date on both my computer (Windows Vista) and iPhone. When I plug in my phone, it charges through the computer, but the computer itself doesn't acknowledge the phone, so I can't sync it to iTunes, nor can I remove any photos from the phone.

I've tested the cable and it's fine, it works on other computers and it allows the phone to charge through the computer. The USB ports are also all fine and I've tried out various other bits of hardware that have all worked fine.

Any ideas on what the problem might be please? Thanks so much!