pcmanfm does not accept/recognize anymore external devices or partitions

[farinet at arcor.de]

Since very recent, on a powerbook, pcmanfm does not open anymore 
external usb sticks. It sees them but when i try to open i'm getting:

	Not authorized to perform operation

The same happens, when i try to open the bootstrap partition.

I'm even unable to do this if starting pcmanfm as root or by gksudo. 
Before this was possible without any problem.

Moreover, pcmanfm doesn't mount audio cd's. I'm not sure if this is also 
recent or not, since i didn't try it before. The error msg in any case 
is different:

	Ort kann nicht eingehängt werden (= Cannot mount device)

Where can i check to repair this?

Thanks a lot in advance!