Uninstall any fonts you may have installed recently.
Uninstall Photoshop using its uninstaller. then reboot.
then install Reg Vac
http://superwin.swmirror.com/regvacz.exe
Just put it in novice mode and hit clean registry.
after its done reboot again.
Then try reinstalling photoshop.
If that doesnt work you might have to go into reg vacs expert mode andf play aroudn with software vac to cleain up any shared DLLs that might be corrupt.
Also do a full chkdisk if you havent done one lately.