Sometimes problems like this come down to drive letter oddities; see for instance http://punkrockhacker.blogspot.ca/2014_06_01_archive.html .

Is your floppy drive A and your CD-ROM drive D?

I suppose I don't have to tell you that Simon the Sorcerer and Discworld work fine in ScummVM.

Yeah, my floppy drive is A: and the CD-ROM is D: and I've tried messing with my config and autoexec by ;ing the lines I added, but no joy.

And yeah, I assumed as much on the ScummVM front, but would like to avoid emulation if possible - I've started another thread for my DOS PC project.

These are authentic, original CDs you're using, right?

Often in cases like this it can be useful to run Filemon, which can identify what files a program is trying to access. It is slightly less overkill than using IDA, as described in the post I linked to.

I don't think anything you put in your config.sys or autoexec.bat has anything to do with this.

Yes, all my games are originals.

I'll have a look at the filemon program you suggested and report back my findings - thank you 😀

I'll bet the problem is the copy protection on the Tiberian Sun and Sudden Strike discs.
Back around 1999-2000 I had an optical drive that failed the disc checks on half the games I tried with it.
They'd install fine, but when I tried to start the games, I'd get a message telling me to insert the CD when it was already in the drive.

People suggested I update the drive's firmware, but there was no firmware update for that model.

I eventually solved the problem by replacing the drive.
Even though it played "unprotected" games just fine, many of the Windows games I played had some form of copy protection it would choke on.

Note that this should be in Marvin. This forum is for old Windows games on modern systems, not old systems or old Operating Systems.

Moved.

collector wrote:

Note that this should be in Marvin. This forum is for old Windows games on modern systems, not old systems or old Operating Systems.

If you were a new user coming here, which forum would look more appropriate for a post
about old games on an old system?

The description of "Marvin" sounds like it's about old hardware, not games.

Marvin
Discussion about old PC hardware and Retro PCs

The description of the "Windows" forum doesn't say it's only for modern systems.

Windows
Getting old Windows games working.

Most people don't deliberately post in the wrong place when they're looking for help,
but I hope you see how the current descriptions would be confusing for a new member.

Overheat, I had a similar problem. You can read the post here.

The only thing I could do was swap the optical drive. While I am convinced it was a specific problem between the the OS and the hardware rather than the hardware its self, I couldn't track down what the specific problem was.

Come to think of it, this might come down to the old "Upperfilters" and "Lowerfilters" problem. Such problems can be attributed to CD-RW "packet writing" software and some CD-ripping programs.

There are lots of guides relating to accessing the relevant registry keys. See for instance https://kb.acronis.com/content/1620 .

Well I have a spare cd drive, so I might try swapping it to see if it fixes the problem. Thanks for your suggestions 😀

I should add that installing a spare CD drive will, among other things, result in the creation of a new device in the registry with blank Upperfilters and Lowerfilters keys, which is why that came to mind. But whatever works.