Deleting USB in registry

I am looking at a Pentium 166 which has USB support in the BIOS but no plate connected to the motherboard therefore it has a PCI / USB expansion card fitted.
USB worked fine with just a modem, but as soon as a USB printer is added you cannot use the modem - port busy.
Both hardware will work OK on their own.
I believe I have traced the problem to an older USB modem that I cannot remove from the registry.  I have removed the card and USB in Control Panel/System/Hardware Settings but I cannot remove in the registry:
HKEY_LOCAL_MACHINE\SYSTEM|CurrentControlSet\Enum\USB or anything below (which includes the old modem references).
I receive the the message: Cannot delete USB. Error while deleting key.  Sorry, no points for advising me to re-install 2000.
Doug
DougNethercottAsked:
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CrazyOneCommented:
BTW with both devices connected does the Device Manager show any conlflicts on either one?
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CrazyOneCommented:
First do a backup of the registry by launching NTBackup and put a floppy in the floppy drive and click the "Create Emergency Backup disk" and then click on "Also backup the registy...". If you have problems rebooting then you need to get to the repair console and do this

COPY /Y C:\WINNT\repair\RegBack\System C:\WINNT\system32\config\

Sounds like the permission is not set to allow this. Open regedt32.exe. Find the HKEY_LOCAL_MACHINE hive and then click on SYSTEM and then click on the menu bar System > Permission and set the permission. Next migrate to the USB tree and do the same there. Now do what you want and then reset the permissions back to the way they were.

The Crazy One
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DougNethercottAuthor Commented:
Hi CrazyOne.
I will award you the 200 points because changing the permissions worked.  Unfortunately I still have the problem - port invalid or busy after re-installing.  There are no conflicts??  Have I read somewhere that some USB printers will not work correctly with a USB add-on card??
The modem loads OK and works, but as soon as the drivers load for the printer (Lexmark Z13), the modem flashes once and then comes up with the error when next used.  Changing the virtual COM ports doesn't make any difference either.  I will give another 100 points if there is an easy solution.  It's not the end of the world because the guy who the PC belongs to can buy a parallel printer - it's just a challenge and I wonder if other USB devices would be affected.  Perhaps I should be aiming the question at the hardware section??
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CrazyOneCommented:
Umm quite frankly I don't have experience using an USB add on cards. Since in this case the USB is not native to the mother board your assumption that some printers won't work with these cards my be correct. Seeing that a lot of the USB printers were developed on the principle that the USB port would be built into the mother board it is possible that a USB printer just doens't recognize the card as being valid. Of course I am just making an educated guess at this point and don't have any facts to base my statements on.

Like on my system the USB is built into the mother board and therefore the BIOS is programmed to see it. I have a printer and a scanner hooked up to the USB ports and both devices work without a hitch. :>)
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CrazyOneCommented:
Maybe you don't have the most current driver for the printer.
http://drivers3.lexmark.com/drivers.nsf/printer+driver/51AFB4629C42164585256AD8006FE706?OpenDocument


Or perhaps the cable is not of the recommended type
USB - Lexmark recommends a V1.0 Compliant Cable
http://www.lexmark.com/US/products/tech_specs/0,1231,MTg0Mnwx,00.html

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DougNethercottAuthor Commented:
I have already downloaded the latest drivers.  I never knew about the cable but wouldn't have thought it was that because the printer works fine on its own.  I e-mailed Lexmark and asked if their printer supported a PCI/USB add-on card but have not received a reply for almost a week.  The guy who owns the PC bought the printer for £30 at Argos a couple of weeks ago and that includes a coulour cartridge - makes you wonder why they were so cheap.
I will award the 200 points but if you come up with anything please let me know.
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