Clock problems with dual boot mac system:- 10.6 and 10.8
The fact that it resets the clock is usually an indication that the PRAM battery needs replacing. Without the PRAM battery keeping things running right, the clock can get messed up plus there can be all sorts of other wierdness that can be difficult to track down. With a machine of this age, it is a good idea to replace it anyway, and it seems pretty cheap to do so:

http://www.newertech.com/products/pram_3v.php

As a short term work around, make sure that the "System Preferences" -> "Date &amp; Time" settings are properly adjusted with your proper time zone and the "Set date and time  automatically" boxes selected. This should help with the clock, but fixing the battery issue will make sure nothing else is bad.

After replacing the battery, resetting the PRAM would be a good idea.

OS X Mountain Lion: Reset your computer’s PRAM
http://support.apple.com/kb/ph11243

http://thenextweb.com/lifehacks/2010/12/04/how-when-why-to-reset-the-pram-smc-on-your-mac/

http://www.macexpertguide.com/2012/11/18/reset-pram-mac-troubleshooting/

http://macs.about.com/od/usingyourmac/qt/Reset-Pram.htm