Sleep issue with Citrus Alarm Clock

Have been using the sleep mode since installing Vista, and up until now has worked fine.I use Citrus Alarm Clock to wake me up in the mornings,it has done its job, except for the last two days.Luckily I have a backup alarm.Basically it doesnt seem to wake from its sleep.As soon as I wake up, I move the mouse and PC wakes up, alarm (music)is playing .

Do you think it could be a software problem? Even though it has worked as described up until a couple of days ago. Must add I also had a problem with Vista not going into sleep mode which has been fixed.