Ok bud, the appliction that you tried to intsall was called USBhost mode. This should update your usb drivers, however your installation appears to have failed according to your post...
http://talk.maemo.org/showpost.php?p...;postcount=195

This appears to be the cause of your problems, there is nothing strange here, it is not difficult to put 2+2 together. You have knocked out your USB drivers by trying to update them with experimental software that is in Extras-Devel. (There is a reason why packages have to go through testing phases.)

If you have created a recent backup then try and restore your n900 using backup menu.

If you have no backups, then go back to that thread, read it thoroughly and retrace your steps again.