USB not recognized as 2.0, and intermittently doesn't work

I have an Inspiron 700m. I never had problems until about a week ago when my USB ports started not to function intermittently and, when they do function, they are recognized as USB 1.1, not 2.0. I use some things that need USB 2.0, so I'd really need to get 2.0 again.

I have the two USB ports that come with the 700m. One of them always works, but intermittently started to work as 1.1 instead of 2.0, until now it always works as 1.1. The other one almost never worked until today when, after one of the things I've tried, the USB mouse I connected to it started working. I haven't unplugged it again, and it's still working. Something odd is that while it didn't recognize anything (mouse, webcam, microphone) it always (except from one time) recognized a flash drive.

I've read every post in the forum and everywhere in the web I've found about this kind of problems, but nothing worked (I actually found many posts about USB ports not being recognized, but none about them being misrecognized as 1.1 instead of 2.0...) I run Windows Update, I updated the chipset drivers, I updated the BIOS, I checked for virus, I unckecked the option that allows Windows to shut off the port to save energy... And the device manager does show a USB2 Enhanced Controller, and reports everything to be working fine. There appear to be no energy issues, and there are no IRQ conflicts.

I also tried to restore my system to a previous state, but every restore point I tried fails to be restored. I doubt this has to do with my problem, but it didn't work anyway.

I really don't know what else to try, so any suggestion is welcome...

Thanks!