I had Ubuntu 10.04 (IIRC) on my P7120D and I don't think it suspended on closing the lid. Installing Mint 13 took care of that issue.

Changing distros is a pain, but maybe it'll help.

(The answer may be out there, but the time spent finding it may be greater than trying a different distro.)

tldr; dunno.

HTH!

Cheers,
Scott.