Fatal Error when opening Unity

Bump: Anybody have any idea how to fix this?

Over my network, i attempted to open a Unity project from another computer… Now every time i start Unity up, even though the project isn’t open in another instance of unity, this pops up:

P.S. I have completely uninstalled unity, then reinstalled it. - No effect.

Answer courtesy of Loius

Try killing {ProjectFolder}/Temp/UnityLockfile

Try starting Unity and immediately hold Alt until the ‘pick a project’ dialog pops up.