Why such an old version of Firefox?
User Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.0.11) Gecko/2009060215 Firefox/3.0.11

Whoa!

You might want to upgrade to the latest version of Firefox as that version is SERIOUSLY outdated and no longer supported, unless it is on a system that cannot go higher. You are running Windows 7 so you can definitely run Firefox 27. Is there a reason why you have not upgraded?

As for your question, go to File > Tools > Options and click the Privacy panel, find where it says History then click the drop down box that says Remember history, click Use custom settings for history, then uncheck the boxes marked Remember my browsing and download history and Remember search and form history then finally click OK. Press CTRL SHIFT DEL to clear your history one last time then Firefox will no longer remember your history.

... Use custom settings for history, then uncheck the boxes marked ...

Firefox 3.0 didn't have that in Privacy > Options - the Use custom settings for history feature was added in Firefox 3.5.

Firefox 3.0 didn't have that in Privacy > Options - the Use custom settings for history feature was added in Firefox 3.5.

Ed,

Really? I could've sworn Firefox 3.0 had that already...Actually looking back on it now, you're right. That's my mistake. It happens.

Romit,

In regards to the-edmeister's comment, there's two things I can recommend but cannot attest for since I cannot install Firefox 3 on my computer.

• You can use Never remember history from the same process I mentioned above except choose Never remember history instead of use custom settings for history
• You can start Firefox in Private Browsing mode every time. To do this: go to about:config, search for browser.privatebrowsing.autostart and set it to True by right clicking and selecting Toggle

Personally, I would do the first one. Simple and easy.