Yes, I heard this from our Windows8 workshop leader today, that in effect Microsoft had to "Close" the App Store upgrade section for the last day and a half due to the crush of users trying to access it. The Upgrade in the App Store appeared to open back up around 1:30PM PST (California time); but it may continue to go up and down probably the most down during "prime-time" hours; 7Am-9AM; 5-9PM or something like that when the demand is the highest.
If you still have problems with that machine in a couple of more days, please Google SPECCY, download and Post your results back here so we have a better picture and specs for that machine that failed the 8.1 update and we will look over and try to advise you further.
Cheers!
BIGBEARJEDI