I have a weird USB connection problem.
 

I have a usb printer and a KVM switch plugged into this Slackware box. If these devices for some reason get disconnected, I have to reboot before it will see that printer or KVM switch again after reconnecting. Nothing comes up in lsusb or dmesg if I reconnect any device while the machine is running. If the box is rebooted then these devices work fine until they are disconnected. I'm not sure how to fix this or what to look for. Any suggestions would be much appreciated.

I have similar printer issues - I'm using cups & foo2zjs.
I take it the KVM switch is an issue, as it's disconnecting stuff.

What's happening to me is: Kernel catches printer connect/reconnect (shows in dmesg); udev catches printer; nut no firmware download, therefore no fun. I wrote a script simply to cat the firmware at /dev/usb/lp0. Then it's found. It did work better originally, but this carries on.

USB problem reply
 

The problem may be in that many systems I believe see virtually everything as a file and should be mounted (which usually happens automatically) and unmounted; therefore, when something becomes disconnected the system is not handling the unmount. Some systems do this automatically for you, some do not. This may be what's going on. Hope that helps.