Limited Connectivity Problem: Windows 7 x64. (LAN \ WLAN \ Mobile Broadband all fail)

I have recently been having some trouble with network connectivity on my HP 8740w, Windows 7 x64.
Apparently for no reason, I will go from having no issues to being unable to connect to any network, regardless of whether it is through the WLAN, LAN or USB mobile broadband adapters.
The first time it happened was about a month ago.
I attempted the following at that stage:

• Deactivate and reactivate all network devices
• Delete all network devices, reboot and re-install drivers, reboot attempt connection.

All these methods failed.
In desperation, I did a system restore. This was successful and I was once again able to connect via all methods.

The same thing happened again 2 weeks later.

The only common event that I can think of is that I leave the laptop on over-night at home, connected to my home wireless router, and then when I get to work and bring the machine out of hibernate, it fails to connect to the enterprise WiFi, and of course then does not work at home, or anywhere else. It's as if all the network adapters forget how to work.

Anyway, this happened again a few days ago. However, this time I had no restore points set up. Administrative oversight...
I needed to sort the problem out without the restore.
Here is what I attempted after EXHAUSTIVE internet searches:

• deleting and reinstalling devices
• uninstalling Bonjour service - apparently this can interfere with network devices
• Modifing registry settings:
  Hive HKEY_LOCAL_MACHINE
  Key path SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
  Value name ArpRetryCount
  Value type REG_DWORD
  Value data 0
  Value name DisableDHCPMediaSense
  Value type REG_DWORD
  Value data 0
• running elevated command prompts and doing: netsh int ip reset C:\resetlog.txt
• Removing all anti virus, spyware protection and firewall software.
• Physically removing and re-installing the network adapter card on the M/B
• Uninstall every program on the computer that could possibly be resulting in some network malfunction. (Cisco DNE, Cisco VPN, Cisco NAC agents)

I may have done more in addition to the above, all for nothing. NOTHING WORKED.
The thing that I do not understand, is that it literally would happen like this: I would go to sleep, everything would be working. I would wake up, it would not work. My routine is always the same during the week, I would leave the machine on and connected to the WiFi so that it Could run downloads and back-ups.
Anyway, I needed to service the laptop, which I did (see http://forum.notebookreview.com/hardware-components-aftermarket-upgrades/710582-hp-elitebook-8740w-end-life-rescue-technical-advice-needed-please.html )
After re installing windows and the requisite drivers (same drivers I was using before the fresh windows install) All network adapters now work perfectly!?!?

This really is a most perplexing issue. I would like to know if anyone has any thoughts or experience on what could have caused this, so that I can trouble shoot effectively the next time it happens.
Thanks.