Does not display correctly - Missing right half and bottom of "home page / welcome" page in IE & Opera but not in Firefox

Not sure if this is where I should post this or not, but it looks like an issue similar to others posted here.

Here's my issue / problem:

In Firefox the landing page / welcome page (after signing in) shows a full screen with content & blocks on both the right, left and bottom of the page. However, in both IE & Opera the right half of the theme including the right side blocks and bottom sections are missing. Also, in all three browser, the rest of the pages (add content, mysite pages) seem to work and display content / blocks as define in the theme section. And, all three browsers, I get the same results with the following themes - all of Roople themes, Denver, salamander, and sib.

Also, have install a test site (not with all the modules) but using a Roople theme and the thing that STANDSOUT as different looking at the code is the following in pages that do not display correctly:

Check it out for yourself to see what I mean - web site is www.allas1.net. Again, the problem seems to be only with the main landing page (home) and the welcome page after signing in.

I have not added any new modules in the past few days, have been in a testing mode (getting ready to launch next week - hopefully) but not a 100% sure that a flag did not get reset during the process, but have checked everything I know to check and did not see anything "odd".

Again, I am sorry if this issue does not belong here. If not, please point me to the forum that this issue would apply.

Thanking you in advance for your help.

Garland P