Headphones not being recognised on re-connection.

Hi Win7Forum, Problem using headphone socket.
I have two 'virtually identical' old Chinese Netbooks, both running Win7 Pro - originally XP.
2Gb Memory, 250/512GB HDD.
Both have identical hardware, BIOS and virtually all the same software installed, especially drivers such as audio, chipset etc.
After booting both machines from scratch:
1 Using any pair of headphones on first machine is no problem, repeatedly plugging them in switches off the internal speakers and sound as expected comes out of headphones.
2 Plugging same headphones into second machine works ok until first time they are removed from the headphone socket. After removal, reinserting the headphones into the socket results in silent headphones and sound continues to come out of the internal speakers.
No message is coming up on either machine saying "you have connected / disconnected etc" but the first machine works perfectly whilst the second machine misbehaves.
Volume levels working fine, no yellow flags in either device manager.
Tried removing audio device driver on both machines, and letting win7 install its own default with no change in behaviour.
Installed the Realtek audio driver that seemed to be supplied with original machine, again no change - still silence on second machine. Not sure it should actually be a Realtek driver.... but that same driver works perfectly on first machine?

Obviously the headphones and headphone sockets themslves are working properly but second machine is not recognising the headphones being reconnected.
I can't think where else to look.
Help appreciated.

Don't if I can help but, when you go into Control Panel, Sound, Playback on the problem machine, are the headphones shown?

hi W2,
thanx for ideas, but....
Control panel/sounds/playback -
OK first machine has Speakers (default device) and Line 1 Reallusion Virtual Audio (ready)
No good 2nd machine has just Speakers (default device) only.
Neither machine has any mention of phones, whether plugged in or not.
Tested using same sound files on both mcs, using both vlc player and win media player.

I'll get details of driver files installed and supply tomorrow.
Thanks so far,

hi w2,
thanx for ideas, but...
The only playback devices on either machine in control panel/sounds/playback are default loudspeakers - doesn't mention any sound card devices etc.
no headphones on either machine even when show disabled and disconnected devices are ticked.
Running out of ideas.
thanx anyway

Would you fill out the system specs for the problem system per this procedure-

System Info - See Your System Specs

reply to wither2
updated sys specs as requested.
I haven't used Internet Explorer for a long time, so had to change default from Chrome to IE11.
I got several script errs, don't know why but seemed to work OK see below:

An error has occurred in the script on this page.
Line: 45
Char; 1146
Error: Object doesn't support property or method 'addEvenListener-
Code: 0
URL: https://www.sevenforums.com' profile. php?do=extra
Do you want to continue running scripts on this page?
Yes No
Then similar message : line 6 char 29 Expected Identifier

Reply to PaulBlack :
Ran batch file as requested:


Hello davet: YOU ARE ABOUT TO RUN MSINF032 - FIND PROBLEM DEVICES?
IMPORTANT: Do NOT close this cmd prompt window while the program is running
Options:
[1] ABORT this process and EXIT.
[21 Run MSINF032 - Find problem devices-
NOTE:
Option [2] creates a Prob_Devices.txt file on the desktop.
>Enter an Option: 2
creating the Prob_Devices.txt file . . .
N0 PROBLEM DEVICES WERE FOUND, deleting the EMPTY file . . .
< Press ANY key to EXIT >


As above, no prob devices were found and the empty output file was automatically deleted from desktop.
Sorry not being much use.....