Hello,
Yes, that tweaking program has caused some serious issues.
I say this because there's only one way that the My Computer entry would be grayed out.
You could try going to Start > Run, and type mmc.
Now choose File > Add/remove Snapin, double=click on Group Policy Client, > Local Computer, then expand Local Computer Policy, > User Configuration > administrative Templates, Desktop. See if the Remove Computer icon on the desktop is configured.. If the Policy is enabled, click Edit and choose Disabled.
You can then go through the other sections looking for any entry that doesn't say"Not Configured.
This is really a long shot, but worth a try