Sleep is, in my opinion, not reliable. All it does is shut down the more power hungry components. When it wakes it will, I guarantee, forget some things. As you've found out. Don't use sleep. Hibernate takes a snapshot of the PC and restores them when coming out of hibernation.
I got a AMD Athlon PC with 2 dvd writer installed, both on sata.
When pc go intnto sleepmode and I want to use again after putting password in and start up, one dvd writer is not shown under my computer icon and can`t be access. I need to shutdown and restart before it works again. My system running on win XP pro service pack 3