Usual reason for this happening with a wireless mouse/keyboard is some
interference from things like mobile phones, DECT phones, other
wireless mice operating in range of the receiver ( had this when my
partner and myself used wireless mice but it only happened when the
two receivers were closer than about 5 ft and/or had direct line of
sight to each other - I use a wired track ball now and prefer it ).
Problem is that once the mouse/keyboard buffers are flooded with
random signals this can freeze the routines serving them so plugging
in any other device is of no use.

Try moving the receiver closer to the keyboard/mouse as this will mean
that the proper signals are likely to be stronger than any external
ones.

BTW - once came across this problem when the culprit turned out to be
a flourescent desk lamp that was radiating electrical noise. Took a
bit of tracking down that one

Even though the keyboard may be unresponsive the RSEIUB procedure to
safely reboot an apparently locked up Linux system usually works but
you may need to plug in a USB keyboard to do it ( may need to unplug
a wireless receiver to prevent it confusing the key presses but the
RSEIUB procedure doesn't use the usual keyboard routines so if these
are locked up it should still work ). The procedure will save any open
files but it's still a good idea to get into the habit of saving work
often .

Hold down [ALT] + [SYSRQ] and keep them held down throughout until the
system begins the reboot at the end. Then press the following keys in
turn, pausing between each one to let HD activity subside or any
screen messages to finish - 10 to 20 seconds should be enough if you
don't seem to have any activity. ( BTW - you will need both hands to
do this ! )

R
S
E
I
U
B

There's a mnemonic to help remember the order: Raising Skinny
Elephants Is Utterly Boring.