In a thread on this forum titled 'AnyDVD problem', Olli said:
== Start Quote ==
Might not be AnyDVD's fault, could be the combination. Please look in your Windows\System\IoSubSys folder for anything not needed and forgottem (NeroCD95.vxd being a bad beast, roxio or adaptec stuff)
== End Quote ==

Hi Olli; can you elaborate on nerocd95.vxd being a bad beast? This file exists on my system, in the stated directory, and I'm sure was placed there by Nero 5.5 which came with my Yamaha CD-RW drive. I'm happy with both, but am concerned for any possible conflicts when I install AnyDVD.

Are you running Windows 9x/ME? If not, you can ignore it. If you do, you might get into trouble. Might, because you usually don't.

Confusing? Indeed, it is. Let me explain:

Some drivers need to sit in the Windows driver stack, and listen/modify I/O requests as they pass by.
This technique is called "I/O request filtering", so these types of drivers are called "Filter Drivers".

There are good reasons for writing a filter driver. AnyDVD is a filter driver "by design" (changing I/O requests as they pass, mainly from "protected" to "unprotected", from "Region locked" to "Region free", and so on).

Writing Filter Drivers is tricky, because a slight mistake can blow up the whole I/O subsystem. Filter drivers can "stack", meaning one filter can sit on another. A filter driver must be designed to never conflict with other filter drivers. On Windows 2000 and XP this is usually the case, because these operating systems have a well designed I/O driver stack.

Windows 9x/ME has stacked drivers as well, but unfortunately Microsoft made a design mistake: They created a table with limited entries for callback pointers. Even worse, Microsoft uses up half of them for their own. (That's why people sometimes get a more stable system, when they delete scsi1hlp.vxd)
Only a very limited number of filter drivers can be stacked on a 9x machine.
Now the driver authors became inventive, and tried to overcome this problem in various ways. I designed such a workaround for CloneCD (Hide CDR Media needs to be a filter as well).
Unfortunately, sometimes "being inventive" means "being incompatible", so it is possible, that if you run out of IO Stack locations, Roxios "invention" together with Neros "invention" can blow up my (CloneCD, very likely AnyDVD as well) "invention".

Depending on what drivers are left on your system (Roxio likes to leave their garbage in Windows\System\IoSubSys), what "filtering" applications you installed (AnyDVD, CloneCD, Blindwrite), what packet writing software (InCD, DirectCD) you have installed, you can blow your I/O subsystem.

To make a long story short: You can delete nerocd95.vxd. It is only needed for the Nero MultiMounter (which needs to filter requests as well).
You can usually delete Scsi1hlp.vxd as well, freeing up 1 callback pointer.

But I didn't want to scare you: Under "normal" circumstances Nero, AnyDVD & CloneCD should not cause any conflict or trouble.

Olli, thanks for the excellent explanation .

Sorry, I intended to include in my original post that I'm using Windows 98 SE. Actually, I'm multi-booting and have Windows XP available as well, but this software is installed on 98 SE.

As to the Roxio stuff, that's on my older computer, and never got installed on this one (whew) . In fact, there's very, very little in my IOSubSys folder that wasn't placed there by 98 SE, so I should (hopefully) be very unlikely to run into trouble when (if) I install AnyDVD. I say 'if', because I'm trying to decide on a good software combination, as I posted in a separate thread.

But, I'm curious as to what the Nero MultiMounter is? Perhaps I'm using it without knowing the name?