Me too got the same problem, but mine arose from me installing 32 bit onto my computer as was not too sure which disc to use, so I followed the install instructions by using 32 bit disc first as it says it would let me know if I needed to use 64 bit first,
BIG MISTAKE!!!!!!
After installing 32 bit and everything working fine I then found out my laptop can take 64 bit so was advised to install that, did that and the apps would then not work and computer ran so slow so currently trying the reset option and now at 56% after
4 hours!!!!
Why do MS say put 32 bit disc in first as it will tell you if you need to change it when it does not do what it says on the tin!!, upgrading to windows 8 has currently wasted 3 day of my life with installing and updates, hope this reset to 64 bit works
or its going out the window and gonna dust off my XP discs as never had problems with that OS, Good luck to everyone in same position as me, its like watching paint dry, Woo-hoo!! now on 57%