What you really need is a screenshot - which your system doesn't permit me to attach. If I try to describe the problem: after the dropdown items like "open file" "save page as" etc., in the "files" "tools" and "help" menus there are strange looking black blobs. The problem is visible on multiple computers, mostly running under XP. I use a variety of antivirus products, Kaspersky, Norton, paid versions of Avira and Avast. None of them are detecting any virus, but in the past I have seen badly infected computers exhibit this phenomenon.
Here is a screenshot. Resolution is not great but the little black rectangles after the dropdown menu items are clearly visible. Maybe they are even characters drawn from a font. The background is the Firefox help page - I hope this meets your criteria. The black marks on the menus are a constant feature, no matter which page I browse to. I first noticed them shortly after upgrading to version 4.0, maybe even immediately thereafter. I have now gone on to 4.0.1 and the upgrade made no difference. I repeat from my earlier post that none of my various antivirus programs have noticed anything amiss. I use due care and browse mostly "plain vanilla" websites - nothing associated with criminal or black-market activity as far as I know.
I had this issue also under XP but with other programs: the same ugly black lines your screenshot is showing. As far as I know it's not a virus or something like that but it has to do with the graphics software in combination with OS. I am now on Windows 7 Prof 64 bits and new graphics card and software and all those black artifacts are not there anymore.
I will have to re-confirm on Monday that the same problem exists under Windows Seven Professional on my work computer. Most of the time I boot it to Win XP and the "black blobs" definitely exist under Firefox 4.0 there, but I will re-check Win 7 before responding further. Thanks for your input.
OK - subsequent investigations reveal that -
a. The black marks are not visible under my workplace installation of Win 7 professional, with Firefox 4.0.0 installed. (But note - that partition has two antiviruses installed - because I didn't realize initially that the Microsoft supplies its own.)
b. Under Win XP the black marks disappear when I reinstall Firefox 3.x but immediately return if I put back 4.x .
c. As an experiment I reloaded a 3-month-old Win-XP partition backup on one of my machines (I never rely on system restore.) To my surprise, when I installed Firefox 4.0.1, there were no little black blobs. I'm waiting to see how long that lasts. If, in a few days, the blobs are back, then I must conclude that I am indeed dealing with something infectious. Strange that my antivirus doesn't see it. I guess this agent is designed to be very stealthy, and only some quirk in the FFox 4.x coding makes it show up by turning the ellipsis <...> into a black blob monolith. Can a virus attach itself to a font? Or maybe this creature preferentially attacks FFox 4.x .
Anyway (c) disproves the theory that the blobs come from the operating system, unless they result from MS-propagated "updates" over the last 3 months that have not yet been installed on the resurrected partition backup.
Can anyone suggest how I should go about reporting this to Kaspersky, Avira, Avast? All of them scan me as clean. I can't just pack up my whole 12-MB of Firefox code, e-mail it to them, and expect them to sift through it.
The appearance of my recently update Firefox 4.0.1 then become ugly. The graphic format from any site were display in a poor appearance like box or vertical lines instead of nice color. Please advice me how I should do to bring back to normal.
Sorry, Bambang_sur, there is nothing new I can tell you. I think the small number of comments here indicate that it is not a common problem. Your situation sounds more visually ugly than mine. For lack of a better explanation, I suspect it is something infectious that attaches itself to elements of the browser and thus becomes visible. I wouldn't use that browser for any confidential logins, if I were you. I have yet to see it make an appearance when Firefox is running under Windows 7, only XP. If it is an issue with the browser, hopefully the problem will disappear in subsequent releases. But I doubt it. Please let me know if you solve the problem at your end!