Firefox opens a lot of files at startup, including numerous add-ons, and either your home page or your previous windows and tabs if set to restore your previous session. So there are a variety of potential sources of this warning.

Does avast! provide more detail about the location on disk (or the URL) of the script that is tripping the alarm? When I search on the web about this "infection" most of the leads point to one particular ad server: cdn-s3.cogmatch.net. No idea whether that is relevant to your situation.

Hi jscher2000,

No avast does not give any hint of where it is coming from all it does is try to get me to upgrade which of course costs money. I went into avast and found a "browser cleaner" I ran that and it seems to have solved the problem, at least when I got out of mozilla and back into it no warning message came up so hopefully problem solved. Thanks for your advice.

Hi jscher2000,

Sorry but problem not solved - I am still getting the virus message and this time I did take more notice and avast did give me some information about it.

URL: http://cdn-dccs.com/js_f.php?v Infection: JS:Iframe-DHY [Trj]

I hope this info helps you guide me to a solution.

Many thanks.

Searching for that server I found a related thread over here: http://forums.majorgeeks.com/showthread.php?t=282534

Could you check whether your preferences contain this server name?

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste dccs and pause while the list is filtered

Anything show up? If so, please copy the preferences and paste them into a reply (right-click > Copy) and we can suggest what to do about them.

If the problem is caused by an extension, you may need to remove it. At this point, I'd just be guessing because you didn't include a list in your More System Details.

Open up the Add-ons page, using either:

• Ctrl+Shift+a
• orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then consider whether you know it is useful and remember installing it. If not, disable it and if it looks suspicious, remove it. (Sometimes a Remove button is not available, when the extension was installed externally. We'll come back to that)

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Does avast! still object?

Since the site is flagged by other security services as a source of malware, you may need to do some scrubbing. This article lists tools other Firefox users have found helpful as an adjunct to their regular security software: Troubleshoot Firefox issues caused by malware.

It's also worth looking in the Windows Control Panel, Add/Remove Programs, for recent installs. Click the Installed on column heading to sort by date. Anything sketchy here?

No nothing showed up

Only have avast online security and flash player 11active. Have skype click to call 6.11.0.13348 and microsoft.net framework assistant 0.0.0 disabled so don't think there are any problems here.

I looked in Windows Control Panel, Add/Remove Programs. Not sure if these might cause a problem but I have removed them just in case. Gimp 2.8.10 which I install the other day and Browse Smart (not sure where that came from)

Hi jscher2000,

I downloaded Malwarebytes - Anti Malware and ran a scan - it told me it found 24 objects. They all seem to be the same thing but with different extensions. An example (I tried to do a screen dump of the list but could not get the image to load) is this PUP.Optional.BrowseSmart.A or PUP.Optional.InstallCore.A etc., etc. I have deleted all files.

also get a program called ccleaner, it will remove any left registry values from said spyware etc. but really avast is pretty useless, your best bet is run windows own defender. what you could do is a system restore to a point before the issues started. cause definitely sounds like malware.

Hi albundi2k,

I tried windows restore a couple of times but it told me it could not do the restore. I downloaded ccleaner and ran that which seems to have helped. I have opened 3 sites in mozilla and no virus notification so far, so may be problem solved. Will let you know how it goes tomorrow - going to bed now it's 12.33am here, way past my bedtime. Thanks for you help.

Hi albundi2k,

Ccleaner seems to have worked, I have opened a few things with mozilla this morning and so far no virus warnings which is great.

Thanks heaps for you advice.

Keep Smiling Bill.

no worries

Hi albundi2k,

Me again - I started to get the virus messages again but only when I logged on under one particular name on the computer, so what I have done is remove the entire person from my computer and recreated a new name and log on etc., etc. So far all is good and no more virus warnings. Hope it continues.

Thanks again Bill.