Create another user. Log in as that user. Put the machine to sleep. Wake it up. Pinwheel? Then it's likely either a hardware issue (3rd party RAM?) or a system issue (you could reinstall, if you wanted to) or a 3rd party kernel extension that is causing the issue. OR, it could be re-acquiring network connections (wireless?)
No pinwheel? Then it's probably something relegated to your primary user's Library, which means you have a lot of work ahead of you trying to figure out what it is, but ultimately faster than a reinstall, which wouldn't fix your problem anyway if it's in your user Library.