Intermittent Sleep problems on all Windows versions I have tried

Never saw a Macbook Pro;

You Can Google search "Macbook PRO" Windows+sleepfix

Copy paste that into the search & Check various yourself

This one received positive response but seems on the Mac side.
http://www.gcsdblogs.org/roodhouse/?p=746
The fix for this problem can be found in the NETWORK panel of System Preferences. Click on the Ethernet Connection
If this service was already marked INACTIVE simply switch it back to MAKE SERVICE ACTIVE and then hit apply.
If it was already set to active then Click on MAKE SERVICE INACTIVE then hit apply.
Now restart your computer. After the restart go back to this same screen and click on MAKE SERVICE ACTIVE, now make sure to hit apply.
This will fix the sleep problems on a Macbook running 10.5.7. Interestingly it also fixes the sleep problems with a Macbook pro running 10.6 Snow leopard.

http://www.itworld.com/hardware/69612/apple-issues-fix-macbook-pro-sata-interfac e
Just found that disabling the "wake-on sleep" option of my mouse, network and modem seems to fix the problem.
It may just be that my mouse or some other device tries to wake up the PC while it is going to sleep, and the computer gets all confused.
-------------------------------------------------------------------------
I've been using hibernate as well from the time I first got my macbook. It's really nice to be able to hibernate, boot into OS X, then shutdown OS X and resume the Windows session without having to go through the whole boot process. It's too bad hibernating OS X forces you to wake up in OS X and you can't choose which OS to resume.
-----------------------------------------------------------------------------
Turning off AirPort usually will allow the MBP to sleep, but not always. In those cases, sometimes I have to try two or three times to put it to sleep -- and for whatever reason, it typically takes 30-60 seconds after disconnecting from the wireless connection before it will sleep. (And, yes, I have already disabled SafeSleep.)
--------------------------------------------------------------------------
For Windows side,from me: a)check all power settings that refer to sleep/disable, this includes doing it at device/adapter level; if you open network conections from C. Panel, right click active adapter(LocalAreaConn.), select properties,then configure "connect Using" you'll see variable power setting.You can see this variable setting in Device Manager as well.