Solved my Windows 8 problem
I have been having similar problems with Android SDK manager not starting in Windows 8. Tried altering Java paths and messing with Android.bat etc. etc. but am now convinced the problem is with the UAC of Windows 8. Why?
1) Originally installed Eclipse in a sub dir of Program Files and found that I could not edit any sub dir there (like Android.bat) because of User Access Controls (UAC)... got me thinking...
2) So re-installed Eclipse in a sub dir under my user, and bingo... SDK manager works fine now.
It is possible to disable all UAC in Win 8 Pro using secpol.msc, but I don't have Pro version and it's not in bog standard version... However, you can still edit the registry to give all apps admin privileges but seems a bit drastic to have to do this...