Yatta!
Okay, I will try and remember all the things I just did to make it work. It has been a sharp learning curve.
First of all, like you (Qbix) said to, I did mount c c:/oldgames in the AUTOEXEC, closed it, saving the changes and opened Dosbox again. It had worked but When I tried to change it to C: it refused. Ah-HA! I thought and typed in mount d d:/ to see what would happen and it gave me the same old bollocks about the D directory not existing. So to conclude I am pretty sure that the keyboard is to blame. There is simply no way on Gods green earth that I can get this keyboard to type a colon on Dosbox. If I want to type a colon I HAVE to do it in the AUTOEXEC.
There you are. Problem solved. It is a bit of a pain in the A but here is the little adventure I had trying to get an actual game to run:
First I put mount c c:/oldgames then below it typed c: which is all the colon antics needed to run a program. Then I opened Dosbox and chose a program. The first one I chose was Geisha because I know the game works from running it in normal DOS but it always ran to fast and I had the same colon crisis with MOSLO. It ran on the second attempt at the proper speed. Good. So then I went for the big money. The whole reason I have spent the last two days trying to get Dosbox to work is because I want to get my copy of Monkey Island running with sound. So I did the same again. I opened up Dosbox with the two autoexecutables I had already prepared (made shortcuts for both the AUTOEXEC and Dosbox on the desktop) and typed in cd monkeyisland hit return and it didn't work. So I took the .exe file out of the folder and put it in the oldgames file. Raw. Then I just typed monkey (the name of the file) and hit return. It said 'Insert disk 1'
Not to be disuaded, I went back to the AUTOEXEC and retyped mount a c:/ (because I was under the impression that I could trick the computer into thinking that it was coming from a disk (see Dosbox readme)) but it still asked for the disk. 'Tits' I thought but I was well prepared and already had a copy of Monkey Island 2 (which wouldn't run in normal DOS because it said the soundcard didn't work). So I went back to the original mount settings in the AUTOEXEC and then in Dosbox: cd monkey island 2 thenmonkey2 and it worked! Well, sort of. It has copy protection so I need to print a code wheel before I can run it. Anyway, it had sound and stuff so I was almost there.
Finally I tried Indiana Jones: Fate of Atlantis. This worked perfectly. Mind you it worked on normal DOS as well but without the sound. This time it had music and I have yet to see if I can get SFX on it as well but it was near as damnit.
To conclude again. If you are using a Japanese keyboard (I am using a Sony Vaio laptop) and you can't type properly on the Dosbox screen then you have to mount the directory and change the drive in the AUTOEXEC. That way you have more control over the keyboard commands. Either that or I am just a complete spastic and was doing something obviously wrong all the time. Bear in mind that I am using a Japanese OS and I am not Japanese. And I am typing with a stick with a rubber bung on the end which is strapped to my head.
That was a joke.
Thanks to all the people who put their suggestion forward today. It is pleasing to know that people go out of their way to help someone out who they don't even know. Especially Qbix who by the look of it troubleshoots for almost everyone on this forum. If you are ever in Tokyo, I owe you a sake.