I used to have Eclipse 3.5.2 working from my Limited User Account (i.e. not Administrator).
But when I upgraded to 3.6.2, Eclipse refuses to run in the Limited User
I had this problem when trying to create a workspace in a mapped network drive.
One option is to start Eclipse from terminal with ./eclipse -vmargs -Dosgi.locking=none.
Another option is to add osgi.locking=none to the config.ini file in Eclilpse's configuration folder.
The second option is more convenient, but has the side effect of allowing any number of Eclipse instances running the same workspace.