T510 keeps resetting during boot unless started in safe mode first

Question

This is an odd, and annoying, one. As of about 3 months ago, my aging T510 started resetting during the boot and startup process, usually while the initial Windows loader was still running, but sometimes it would get beyond that to the Windows startup screen before resetting. When it does so, it's with an audible click, and then it goes right back to BIOS boot. It has been getting steadily worse to the point that it can take up a dozen tries before it manages to complete startup. Once it has succeeded in doing so, it seems to be stable. However, if it goes to sleep or hibernates (manually or on low battery), it has the same problem trying to wake up. However, if I start up in safe mode, and then restart normally, it comes up OK every time. After a safe mode startup, if it has been off for a short time (one or two minutes), it will still start up OK. However, if it has been off for several hours, then the problem reappears.
It seems like some piece of hardware on the motherboard isn't initialising properly on powerup, but starting Windows in safe mode seems to sort it out.
My machine is a T510 4313-CTO, bought in March 2010.
Can anyone figure out specifically what's happening, and, more importantly, is it fixable?

Answer 1

OK, I spoke too soon. Started it up this morning (in normal mode), and it reset again, so I restarted in safe mode, and looked at the Network Adapter list in device manager, an lo and behold all the WAN devices that disappeared after I disabled them then re-enabled them yesterday had reappeared, so I disabled them again, and restarted. This time as before, it restarted OK. The devices listed were:
1394 Net Adapter
Bluetooth LAN Access Server Driver
Bluetooth LAN Access Server Driver - Packet Scheduler Miniport*
Direct Parallel*
Intel(R) 82577LM Gigabit Network Connection
Intel(R) 82577LM Gigabit Network Connection - Packet Scheduler Miniport*
Intel(R) Centrino(R) Wireless-N 1000
Intel(R) Centrino(R) Wireless-N 1000 - Packet Scheduler Miniport*
Keith & Koep USB Remote NDIS Network Device - Packet Scheduler Miniport*
Tom Tom - Packet Scheduler Miniport*
WAN Miniport (IP)*
WAN Miniport (IP) - Packet Scheduler Miniport*
WAN Miniport (L2TP)*
WAN Miniport (PPPOE)*
WAN Miniport (PPTP)*
The devices marked * were hidden after successfully restarting in normal mode, although before they showed no yellow "!" before, which is the usual reason for showing normally hidden devices.
All the Packet Scheduler Miniport entries were apparently due to the QoS Packet Scheduler driver which is installed on Windows LAN port by default, although it's rarely useful (see http://forums.speedguide.net/showthread.php?190110-Qos-Packet-Scheduler for some background). Anyway, though I tried uninstalling it (which got rid of all the Network Adapter devices followed by " - Packet Scheduler Miniport"), it still didn't cure the problem.
That was solved following Les Bell's advice at http://securitasdato.blogspot.co.uk/2011/05/infamous-packet-scheduler-miniport.html concerning correcting the driver version numbering in the registry (I had exactly the same error). Searching through the registry in the way he suggests is a bit of a faff. I found all the relevant entries under the key HKLM/SYSTEM/CurrentControlSet/Control/Class/{4D36E972-E325-11CE-BFC1-08002bE10318} (and the same under the numbered control sets). All the usual caveats apply, i.e. don't edit your registry unless you *REALLY* know what you're doing, at your own risk, etc.