Unable to access DVD/CD Drive

This is the second time this problem has occurred. The first time I did a complete restore which resolved the problem, I see little point doing that again as the problem has recurred.
I am unable to access my DVD/CD Drive, in Device Manager I can see the drive showing a problem, on its properties I get:
"Windows cannot verify the digital signature for the drivers required for this device. A recent hardware or software change might have installed a file that is signed incorrectly or damaged, or that might be malicious software from an unknown source. (Code 52)".
I have certainly not made any hardware changes and am not aware of any software changes.
I have the following drivers installed:
Cdr4_xp.sys (shows as not digitally signed)
Cdralw2k.sys (shows as not digitally signed)
cdrom.sys
GEARAspiWDM.sys
PxHlpa64.sys
Can anyone advise what the problem may be and how I can approach resolving it? I would remove each driver in turn until the problem goes away but I am unsure of the steps to take.
Help!

MartinR, welcome to the Seven Forums.

Looking at what those various drivers are for,

Cdr4_xp.sys (shows as not digitally signed)
Cdralw2k.sys (shows as not digitally signed)
cdrom.sys
GEARAspiWDM.sys
PxHlpa64.sys

the only one in the list that is an actual system file is the bolded one. The rest are from either Sonic, Roxio, Gear Software and/or iTunes; with one of them that is causing the problem, take your pick as to which one. Basically comes down to too many different programs installing their own drivers and canceling each other out.

I would start with deciding which of them you want and/or need and remove the rest. Once you start removing them that error will probably go away.

Hi Stormy13, thanks for that. Can you advise please on the best way to remove the drivers in W7? I would like to remove them one at a time until it starts working again so I know where the problem is.
Thanks

Can anyone advise the best way to remove individual drivers please? I have removed one of them from the registry but it's now giving me the message "Windows cannot load the device driver for this hardware. The driver may be corrupted or missing. (Code 39)". I still have 3 drivers showing, having removed Roxio;

Cdralw2k.sys (shows as not digitally signed)
cdrom.sys
GEARAspiWDM.sys

but I don't know which one is causing the problem. I would like to get to the point where I only have cdrom.sys loaded but not sure how to get to that. Any advice?
Thanks for all your help so far.