Originally Posted by toddos
Cybmole, turn UAC back on. There's no reason to turn it off, and doing so can cause other weird problems..
off topic but there are several excellent reasons to have UAC off.
One is that the the backup registry utility ERNDT can run at startup - without USC flagging it as an unkown prorgram.
ditto for running peerblock at windows startup.
ditto for pinnacle game profiler.
NB there is no way to ""train " UAC to quit asking the same question every time you use a safe 3rd party utility, so when it does like like one of the above, or does not like e.g. JKdefrag ( another excellent freeware utility) you have to manually confirm EVERY time you want use the utility, or write complex auto-schedule script workarounds.
I have encountered zero weird problems - UAC is an OPTION so those who enjoy being nannied by microsoft can leave it on, those who don't can disable it.
back to on-topic, I suspect that UAC does not have calibre on its approved list as it is expensive and difficult to get microsoft to sign an installer for you.