I am running Ubuntu v7.04 with a GNOME desktop:
When I attempt to open the Network-Manager GUI, it opens, but only after about a one minute plus wait. Then, only a window shows up- nothing inside the window displays. Approximately 5 minutes later, I might see the contents of the window and may use the application. To better explain what this looks like, Imagine the Network-Manager GUI. Now picture a light gray area in the back, with an empty white box in the middle where the networks are supposed to be listed. There are no buttons. The title bar appears, and there is a defined border and outline. This is there for 5 or more minutes.
This problem seems especially severe occasionally, when it sometimes crashes or freezes without ever fully loading (as in, before showing the contents of the window).
I have looked at the CPU and Memory usage logs: the CPU usage is never above 78%, and the memory usage does not cross 214 MB, when I am opening the application. If it helps with the resolution, I have 478 MB of RAM and a 2GB Swap, as well as a 3.07 GHz Pentium 4 processor.
I have recently edited the /etc/network/interfaces file, as well as the file where the DNS address is stored (I do not recall what it is called), before the issue began to occur, though I do not think it is related to the problem.
Due to the fact that I have not found a cause or a resolution, I ask for help or advice in resolution.

Are we to assume your network connection is wireless? The delays may relate to timeouts trying to connect. Is this a new install? Did it ever work? Tell us what your hardware looks like and what you did prior to your problem appearing.

The connection is not wireless: it is a standard wired connection. Yes, at first it did work. The problem began shortly after I edited the /etc/network/interfaces and the DNS files. I did make the DNS read only, since after each boot it was reset. After setting everything back to how it was after a fresh install, the problem continued, so I redid my alterations.
As to my hardware, I have a Toshiba Satellite A25-S3072 Laptop, which has a Pentium 4 3.072 GHz processor, and 480 MB of RAM, as well as an Ethernet Controller (100 MBs).

Your system is acting very strange and I haven't seen these symptoms myself. DCHP is almost always a better choice than manual configuration of DNS. That allows your ISP to make changes to DNS servers to accommodate network changes. As rule its no longer necessary to manually edit these files although I might recommend that you disable IPv6 for now. Ubuntu and others attempt IPv6 connections to DNS before trying IPv4. IPv6 always fails but the distros are ready for the 4 to 6 transition that no one wants to make. Once connected to a site, IPs are used which makes things faster. Waiting for IPv6 to time out adds delay to all DNS access. Also network performance can be an ISP problem. Comcast in Fresno for example occasionally slows to sub-dialup speeds. Their performance is erratic but usually fast enough to get the job done. When this has happened and I call they have reset my connection which made an instant improvement. Recently they couldn't ping my modem so I bought a new one. Part of the issue is that cable is a bus structure like a LAN and as use and # of users increases performance goes down. Firefox has an extension Bandwidth Meter which I've found helpful in diagnosing network problems.

Thanks for the help: It worked. It seemed that the program was getting caught in an attempt to connect with IPv6. There is also a network performance issue (About the tenth time since Comcast became my ISP), but I should be able to fix that. Overall, disabling IPv6 works to fix the Network Manager GUI.

Glad I could help. I highly recommend the use of bandwidth measurement to help identify problems and to have additional information when calling Comcast. If you don't use firefox there are also some web sites that serve the measurement purpose. The measurements vary from service to service but even if the #'s are questionable the trends in performance decline aren't. If you watch you'll notice that from time to time Comcast will quietly improve the performance on the cable run you share with others.