Do a malware check with some malware scanning programs on the Windows computer.
Please scan with all programs because each program detects different malware.
All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender: Home Page:
  http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

it looks like user.js is currently active in Firefox. The user.js file is only present if you or other software has created this file and normally it wouldn't be there.

You can delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in the current Firefox release. You can get to the profile folder below:

• Help > Troubleshooting Information > Profile Directory > Show Folder

or

• Go to about:support and click Show Folder next to Profile Directory.

That is a pretty weird file. Who would code a word like length this way:

['lzu'.replace(/[zu]/g, '') + 'eJZnxgOKtME'.replace(/[JZxOKME]/g, '') + 'h']
['lO2eRnGigi7ti'.replace(/[O2RGii7i]/g, '') + '\x68']

Hi thank you so much for your help ,ran suggested anti /clean programs and they did find more hidden things than currently installed programs now this is still part of original error mssge c:\program files (x86)oldfirefox\browser\plugins\firefox.exe.. Guy said he checked old pc before transferring but who knows eh , just need to find out what to delete ok again thanks so much I know how to fix houses well ,but this pc stuff takes me along time ok again thanks ,cheers kaz