Does USB work now ?

Yes it is, at least it is not anymore an eletrical/hardware problem, I'm now struggling to make my WLAN USB adapters recognized as proper wlan radios.

The software fixes didn't stop the issue for me (although I set the txpower to 10dbm my USB device gets frequently disconnected). Even with deactivated wifi my USB device is resetted. I don't feel competent enough to do any soldering so if there is any kind of software fix I could try I'd really appreciate any ideas.

Then your carambola module or motherboard is broken.
Write to info@8devices.com how to exchange to new devices.

Just wanted to say that I have/had the same problem with a USB stick disconnecting all the time.

It seems to be OK with the new image now. I'm just wondering how high I can turn the txpower before the problem shows up again. I'll give that a try soon.

So, actually I had some observations myself, which couldn't be explained by what was already described here.
In my current setup, I'm using a hub (passive) and some usb sound card (Behringer UC-202).
When I power up the device, having both devices connected, the usb sound only produces garbage (you can actually listen to the playback, but it sounds like played at a fraction of correct speed / pitch).
Just rebooting the system (or replugging) the devices usually solves the problem.

I had to limit wlan tx power to 10 (dbm) to make a enumeration of the devices happen (using the latest available sources).

Guess I'll have to put an extra cap in the usb's vcc line.

For now there is another solution than reducing txpower read this forum thread: viewtopic.php?f=5&t=161

Next month (at least we hope so) wee will have even better solution - mass produced RF shield (download/file.php?id=68&mode=view). Looks like it solves all wifi/usb issues.