Are my PC's USB ports losing power?

[theTastyCat]

Here's a weird one for you. I regularly USB-tether my TP2 to my desktop for internet sharing. Starting this week, after a while the amber charging LED would turn off, and though Internet Sharing would still show "Connected", the computer wouldn't recognize that the phone was hooked up. Restarting the computer fixes the issue for a while.

Just now I did an experiment - once the PC failed to acknowledge the connection, I unplugged the PC end of the cable and plugged it into a different PC, and the amber charging LED turned on. Back to the first PC - no luck.

Does this sound like possibly a power supply issue? Maybe the USB ports are underpowered?

Would love your input - thanks.