m11x wont wake up from sleep

I recently bought an m11x.  It came with win7 Home but I decided to replace the HD with an SSD and install my own (legitimate) copy of win7 Ultimate.  Everything works fine while the computer is in use however sleep does not work.

If I put the computer to sleep manually or let it sleep automatically the monitor turns off, it becomes non-responsive but all the lights on the machine are on.  If I leave it long enough - say overnight - it actually completely turns off.  It will not wake from this state.  I have to force reboot it after which it starts fine though Windows complains it did not shutdown properly.

I had no such problems out of the box but after my factory HD failed and Dell replaced it and rebuilt it, its had this issue.  I then wiped and rebuilt it with Ultimate and an SSD and the problem persists.  There are no driver issues detected.

Before I ask Dell to come and take a look is there something I can do?  Something I am missing?

Thanks.