04-11-2012, 10:07 AM
It sounds like reloading the OS will probably resolve this issue.
In regards to Snow Leopard to Lion, that depends on what media you have to re-install the OS.
If the machine already has Lion with a recovery partition. Hold down option+R when booting up the machine, to boot to the recovery partition. Or just hold down the option key when booting and you'll get the Apple boot menu - this will show something like: two HDD's, one will be the Mac HD and the other will be the recovery HD.
Or if it is an older version of the Mac OS:
If you have the Mac OS CD, just load it into your super drive and hold down C when you hear the Apple chime when booting up the machine, this will boot from the CD and you can reinstall the OS here.
Once the CD has booted up, you can use disk utility to erase the disk and re-install the Mac OS.
If you go this way, just do a google search: how to reinstall Mac OS from CD.
It is a pretty straight forward process.
Just so you are aware, doing the above will erase all data on the machine