Microsoft Word - serial # conflict

When starting microsft Office, an error message pops up and states something like:

'Microsoft Office cannot start because Microsoft Office is already in use... installation exceeds number of licenses...'

Our office computers are all networked, and we certainly have enough licenses. I verified that each computer has an original license #. Somehow, it thinks that two computers in particular are using the same #. Any suggestions/thoughts?

I am new to trouble shooting these easy types of issues. Thanks for any help.