It would have helped to have the complete error message so I wouldn't have to guess, but rtl120.bpl appears to be related to something called "TuneUp Utilities 2010." Further, some anti-virus applications apparently were detecting this file as a Trojan horse (and thus deleting it or quarantining it) although those "false positive" detections were from Dec. 2009 and I would have expected the issue to have been long since dealt with.
Assuming that you have something like TuneUp Utilities 2010 installed, I suggest that you uninstall it. As a general rule, such utilities don't provided much benefit (other than to the income of the vendor) but have the potential for causing problems to your system. If you can't uninstall whatever it is from Control Panel > Add or Remove Programs, you will probably succeed with free Revo Uninstaller.