Can you attach a screenshot?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

Use a compressed image type like PNG or JPG to save the screenshot.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do NOT click the Reset button on the Safe Mode start window.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Usually a plugin doesn't generate an error if it is not required by the content in the page. Since so few pages use Java, I would think it's something else, but it's easy to disable Java as a test and see whether that eliminates the errors.

Open the Add-ons page using either:

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

In the left column, click Plugins. Then find Java(TM) Platform SE U51 and change the drop-down control to "Never Activate".

Does it help?

If that doesn't help, maybe... The Java installer traditionally bundles the Ask toolbar. If you allowed that to be installed, try to disable or remove it on the Add-ons page.

In the left column, this time click Extensions, then hunt down Ask.

Some other threads on the forum about Type Error:oE (there might be more):

• i keep getting type error:oE is null after firefox starts. after that firefox crashes. - Error doesn't occur in Firefox's Safe Mode, but exact cause yet to be determined

• After years of happily using Firefox, sudden, recurrent calamity - Error stopped after disabling all unimportant extensions, but exact cause yet to be determined

• Erro TypeError: oE is null (discussion in Portuguese; Google Translate) - seems to be resolved by disabling McAfee SiteAdvisor extension

I have also been having this problem, starting today, although my Firefox doesn't crash/close when the error box pops up - I can just close the box and carry on browsing.

However, as with the person in the thread listed above, I found that disabling McAfee SiteAdvisor seems to stop it happening (it happened fairly at random, but in about half an hour of browsing with it disabled, I haven't had the error pop up, compared to within a few minutes when SiteAdvisor is enabled). It looks like there was also a SiteAdvisor update today, so that also correlates with the onset of this problem. Are other people getting this problem using SiteAdvisor? I don't know much about the mechanics of SiteAdvisor - could there be a link with Java too?

Using Firefox 27.0, Windows 7 SP1, McAfee SiteAdvisor 3.6.5, Java 10.45.2.18.

Hi TimKasoar, I don't think anyone has linked this to the Java plugin. Firefox has its own built-in interpreter and compiler for JavaScript which, despite the name similarity, is a different technology.

I see... Had not realised that before!