I'm facing a problem with Comments module. Everything works fine, except one thing - errors display. When I fill the comment form correctly, a comment is added/displayed. When some requied field is not filled or filled in wrong way, the errors are displayed. Till then, everything is as it should be. Problem starts to appear, when I firstly fill the form with errors and then I try to fill it again, correcting requied fields. When I do so, and press "send" again, comment is added. However, the display of errors still remains.
Normally, when the form is firstly filled with some wrong entries, there should be a message informing what's wrong and when the form is filled again, thisa time correctly, this message should disappear. Here, it doesn't. Comment is added succesfully, but there is still message, informing about errors. Moreover, this message is displayed at every place, where there is a comment form. So, even if I go to another page (e.g. another news) and I want to comment it, I can see error message there. So it's like...if there are some errors during form filling, the error message is added permamently to the site. I can write another comment and it will be added, I can go to another page with comments form and I still see errors, I can refresh the page, open it in another tab/window, or even close the browser completely and when I open it few mins later, the errors are still displayed.
Described situation happens in every browser (tried ff 7, chrome 13, safari, opera 10 and ie

I modified the original comment template a bit, but I tested also an original one and the problem is there as well.
Will be grateful for any kind of idea how to solve this.