USB harddisk not recognized after upgrade

[martin@marijg.demon.nl]

Hello,

I am running debian testing and I did a upgrade last week and after that my 
usb harddisk is nog recognized anymore. Last time it did work was november 
10, so it has happend after that date. A older linux on a other partition 
still does recognize this usb drive, so it is not a hardware problem. But I 
want to use my new big disk also with debian testing because that is the 
distro I use daily. 

What did happen and how do I sove it ?

thanks in advance,
Martin