I'm guessing that you are running either windows 2000 or XP.
If so, make sure you have administrator privilages on your login account and write access to the directory that MxO is installed in.
To do this when on a network (ie. at work) you will probably need to be granted local administrator rights on your machine.
To do this go to:
control panel => user accounts
then add your account and set it as administrators (you may need someone with admin access to do this for you)
Thsi will only grant you administrator on your machine and not on the network.
