This is a common Hackintosh issue, you can find more about it by googling "Time Machine fix" (which will mostly come up with the old, obsolete fixes for it) or "UUID error 35". Like AES decryption, SMBIOS and video card injection, getting this issue fixed is one of the fundamentals of a fully operational Hackintosh.
OSX generates the Hardware UUID using part of the MAC address of the first built-in ethernet device. So it follows that for the UUID to be successfully generated, an ethernet device on your system must be "EN0" and recognized as "internal" like on a real Apple computer.
It doesn't matter if it's on-board or a PCI card or whether it's the device you actually use. I don't think it even needs to be able to establish a connection.
On Hackintoshes this often doesn't work like it's supposed to, the OS doesn't find any "built-in" ethernet hardware and you get these problems with some apps not working properly, such as Time Machine and Maya. And you will see UUID error 35 all over your system logs.
Instead of relying on an older, patched version of IONetworkingFamily.kext, you can fix it permanently by adding ethernet device properties (AKA an EFI-string) to com.apple.Boot.plist, or if you're using Chameleon 2.0 RC2, set EthernetBuiltIn=yes (works perfectly on my P4 hackintosh). It can also be fixed by patching DSDT, but the fix has to be tailored specifically for your hardware and only a few very patient and intelligent people know how to do that.

Yes, that means don't ask me.
You could also use UUID.kext and UUIDGenerator.app to fix it but it's not as elegant a solution.
Lastly, some people have managed to get around the issue by injecting a fake ethernet device into the device tree (again, don't ask!)
If there are problems after applying any of the fixes, delete /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist and Preferences.plist and reboot. This will set off a reshuffling of the ethernet device(s) on your system and should place the device for which you applied a fix at en0.