UNIX for Advanced & Expert Users

I am in a multi-user Linux environment at work. Other users easily run processes on my machine when my machine is idle, but when I try to use my machine, it is dead slow. The processes run by them always grab the top spot using 99% of my CPU time. Is there a way I can prevent others to run processes on my machine? When I typed "who", those users are not found in the list, so that rules out using rhosts file for dis-allowing them. Pleas help...

Something is not right here.

Are you your own sysadmin? Who else has or had the root password?
Is there some sort of distibuted processing network that assigns jobs to networked machines or updates your cron file?

If you can access the linux box as root, you can nice those processes so that they do not compete with your jobs. Is sounds like your stuff has very low(high number) priority.

Yes, there is a program which allows users to run processes on machines in the network which are idle. So thats how, someone else ends up using my machine. I do not know the internals of that program, and I am not a sysadmin either.

Then you need to talk to the sysadmin. It sounds like your base priority is lower than the jobs sent in over the network. This is not acceptable - somebody made an error in judgement.

Your only other recourse is to create a dummy process that hogs the cpu and runs all the time in background. Kill the process when you want to run something. This is probably against policy so check first.