what is your dosbox version and where have you got it from?
what is your Operating System?
what are your PC specifications?

post content of "DOSBox Status Window" (in Windows: right click on its title bar -> edit)
enclose your dosbox's config file

post your mount lines and what is written under every mount line
post what is written after you type "mount"

unless it is reproduceable, we don't/can't care much.

Version is the latest and I got it from the links on your page. I'm running WinXPHE SP2. Specs? "Old" I bought it about 7 years ago now.

Fortunately, despite the freeze, I was able to mark and copy:
DOSBox version 0.74
Copyright 2002-2010 DOSBox Team, published under GNU GPL.
---
CONFIG:Loading primary settings from config file C:\Documents and Settings\Angus
\Local Settings\Application Data\DOSBox\dosbox-0.74.conf
MIDI:Opened device:win32
SHELL:Redirect output to nul
SHELL:Redirect output to nul
SHELL:Redirect output to c:\starting.dir
SHELL:Redirect input from c:\starting.dir
SHELL:Redirect output to nul

The conf file was probably the same one that was installed by the installer, but I'll attach it anyway.

The mounts are a piece of cake, and I've posted a screen capture to prove it.

This problem is so reproducible: by me.

The disc doesn't have an obvious title, but it contains both Ultima Underworld and Ultima Underworld II (It's an EA Classic, FWIW). After I mount, I execute the following:

1d:
2origin (not the manual-recommended bat file)

First it warns that it can't detect EMS and promises that the game won't run w/out it. The game runs anyway. After that I think it freezes on the line:

1c:\batcd <c:\starting.dir >nul

I guess that's it.

hmm, maybe I'll give it a try tomorrow. I think I have the same CD-Rom of UW1+2.

check whether following the guide helps
60 seconds guide to getting your game to run in DOSBox

Agh that damned guide again which is probably no use at all here.

Anyway, you could try running 4dos before starting the game. IIRC DOSBox had some problems with redirection in the past.

The installers (INSTALL1.EXE and INSTALL2.EXE) are hanging when they try to produce some beeps on the PC speaker. This can also be seen in the menu selections if you bump the highlight bar against the top or bottom of the menu items. They are reading port 20h in combination with some PIC masking/unmasking that is apparently not giving expected results in DOSBox, and they gets stuck in an infinite loop. When these hangs occur, you can occasionally hear a speaker chirp, giving an audible clue that the speaker is involved.

You would think that if you are careful to avoid doing anything that causes a speaker beep, you might manage to get through the installation. However, the installers beep when there is some error or warning, and they are displaying a message to warn you that you don't have EMS, even when EMS is enabled in DOSBox. The installers successfully open the EMMXXXX0 character device and make several successful INT 67 calls, yet they still conclude that EMS is not present because bit 0 of the CR0 register is not set. With memory managers like EMM386 or QEMM, the CPU is in V86 mode, so the bit would be set; but it is a poor test because it ignores the possibility of hardware EMS, which is what DOSBox emulates. There is some code in DOSBox allowing the system to start up in V86 mode, but currently it can only be activated by changing source code, not with a config setting.

It's a bit cumbersome, but the problem can be worked around by using a memory manager like JEMM to provide EMS and then being careful not to cause any beeps from bumping the menu bar against its limits.

I'm a bit skeptical that it is INSTALL1.EXE. If I run that from the prompt (as the manual recommends), I don't have the crash (but I do have the spurious no EMS warning). The manual doesn't even talk about origin.bat (which means it must be a throwback or something). I wouldn't have even bothered reporting it if it didn't cause my whole computer to freeze.

Hmm, it seems the hang on beep problem is happening with my debug build. Not sure why that is, but there's no issue there; and the EMS warning can be disregarded.

The problem with BATCD.COM occurs when INT 21/0C0A is called to flush the input buffer before INT 21/0A reads the input. The flush loop becomes infinite because DOS_GetSTDINStatus() is always returning true.

1   case 0x0c:		/* Flush Buffer and read STDIN call */
2      {
3         /* flush STDIN-buffer */
4         Bit8u c;Bit16u n;
5         while (DOS_GetSTDINStatus()) {
6            n=1; DOS_ReadFile(STDIN,&c,&n);
7         }

With it stuck in this loop, your system might become a bit unresponsive depending on how many cores you have, but I can still kill the task in WinXP in all the usual ways. Easy enough to avoid the problem by just running the installers directly.

Edit: tested earlier releases of DOSBox with the debugger enabled, and the problem with the hanging speaker beeps appeared sometime after the 0.72 release. Not much of an issue because it only happens in a debug build, but at some point I'll see if I can isolate the change(s) responsible.