It is not happening with me. On your system does the random close happen before you get the popup menu for the right click, or do you see the menu and then the close happens?
I have a similar system. 1.80 gigahertz AMD Sempron, 960 MB RAM, running XP-SP3. I use "open in a new tab" quite a bit but I don't remember anytime that it caused the current tab to close.
In EDIT - PREFERENCES - BROWSING - TABBED BROWSING - GENERAL - OPEN NEW TABS, I have "Next to the last tab" chosen. What do you have there?
Not happend for me in Win2K with K-Meleon 1.5.2RC2 & K-Meleon 1.5.0.
Are you tried to use Tools -> Mouse Accelerators -> Firefox 2 and use middle click to open links in new tab background?
If this is a bug ramdom can be very difficult to confirm it.
It works well like that, but I still have the random close issue when right clicking on links. It looks like it's random, so no way to solve it unless anyone with the same problem appears. I'm also a programmer, and know how difficult it is to find such a bug.
I'm using K-meleon 1.5.0 (I don't like the newer versions...just this one). Whenever I LEFT CLICK on my mouse, I want the links to open as a new tab WITHIN THE SAME window (as is the case in ie 7.0 and firefox 3.5). But instead of opening in the same window as a new tab, the link opens in a SEPARATE WINDOW. Does there need to be some 'tweaking' in the config for this simple task?