BSOD while using firefox, worker thread returned bad IRQL?

Welcome

Bugcheck E1 and McAfee are common.

I'd suggest you to remove McAfee, consider uninstalling it with the McAfee Removal Tool and replace with Microsoft Security Essentials at least to test.

• How to uninstall or reinstall supported McAfee products using the Consumer Products Removal tool (MCPR)
• McAfee Removal Tool - McAfee Uninstaller

Recommended antivirus program for Windows 7 based on stability compared to others:-

• Microsoft Security Essentials - Free Antivirus for Windows
• Microsoft Security Essentials Download | Free Spyware Protection
• Malwarebytes - The Free version
• Good and Free system security combination.

Do not start the free trial of Malware Bytes; remember to deselect that option when prompted.

Run a full scan with both (separately) once downloaded, installed and updated.

Run the System File Checker that scans the of all protected Windows 7 system files and replaces incorrect corrupted, changed/modified, or damaged versions with the correct versions if possible:

• Click on the
• Type CMD on Search
• Left click and Run as Administrator
• Type SFC /scannow

Full tutorial here:

• SFC /SCANNOW Command - System File Checker

Run Disk Check on your hard disk for file system errors and bad sectors on it:

• Disk Check

Free up the start-up, nothing except the antivirus is usually needed.

• Startup Programs - Change
• Troubleshoot Application Conflicts by Performing a Clean Startup

Let us know the results.

Good to hear.

Let us know how things are after a week. :)

Hi :)

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