ok well what happened is that i am trying to install skype on my linux and it's really important and everytime i try downloading it it keeps telling me "only one software management tool is allowed to run at the same time, please close the other application e.g. "update manager, aptitude... " i don't know why that's happening i just wanna be able to download it ... please reply soon thanks :)

This means you have synaptic running somewhere. Close all your open windows and try again. If that doesnt work restart your computer and try again. Make sure nothing is trying to update or install while you are trying to install skype.

Check if it's update-manager which is running when you try to install skype.
Update-manager defaults to periodical background check, so it may be that is was running right them.

O.k. I'm having the same problem. I already rebooted the pc and the problem does not change.

So - How do I "Check if update-manager is running when I try to install" new programs?

open the terminal applications->accssories->Terminal
there type sudo dpkg --configure -a and enter

the problem must be a broken package or a package that failed to download
the above command will take care of the problem.