At work, but not working

I am at work but there are IT problems with the remote machines we work with, so I am not working. I know it seems relaxing, but for some unknown reason, I feel a bit guilty.
Sometimes I am at work and not working, simply because I am tired or just lazy. The task at hand may be difficult (for me, I am not very skillful) so I procrastinate (this is correct but in everyday speech we would say "I put it off").

Do you have good suggestions for me to do while being at work?