After I found out that Atahualpa has issues with Display Widgets plugin, I tried other widget plugins, but, alas, none of them is working.

I tried Widget Context, TS Custom Widgets, Widget Locationizer....

Is there any working widget plugin?

Looks like I found a great plugin - Dynamic Widgets.

Sheesh, what a stress!

Looks like I was celebrating too early

Dynamic Widgets does exactly the same thing as Display Widgets.
Totally messes up my blog (homepage and post pages) in IE and Safari, while all other pages are all right.

Erm, can anyone help with me with this, it is obviously not a plugin problem.

EDIT:

It wasn't a problem with plugin, or theme, but with a certain widget with form in it.