Why won't firefox delete my history searches and cookies and cahce when I click clear history?

Question

There's a yellow triangle with an exclamation mark in the middle and it says "All items selected will be cleared. This action cannot be undone" when I try deleting everything in the clear history tab.

Answer 1

Please ensure that you do not have an add-on or third party program that will prevent Firefox from deleting history.
This can also be the sign of malware or another infection.<br>
Please scan your computer for infection. Here are some great free tools:
Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.
You can try these free programs to scan for malware, which work with your existing antivirus software:
* [http://www.microsoft.com/security/scanner/default.aspx Microsoft Safety Scanner]
* [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware]
* [http://support.kaspersky.com/faq/?qid=208283363 TDSSKiller - AntiRootkit Utility]
* [http://www.surfright.nl/en/hitmanpro/ Hitman Pro]
* [http://www.eset.com/us/online-scanner/ ESET Online Scanner]
Further information about issues caused by malware can be found in the [[Troubleshoot Firefox issues caused by malware]] article.