TYPO3 Core

With troubleshooting mode activated, I can see that an error is generated every time:

• Failed attempt at loading stylesheets ***
  However, stylesheets then load and there seem to be no consequences

Firefox Minefield
php 5.2.5
MySql 5.0.45

[HTMLArea::init]: All scripts successfully loaded.
[HTMLArea::init]: Editor url set to: /typo3/sysext/rtehtmlarea/htmlarea/
[HTMLArea::init]: Editor skin CSS set to: /typo3/sysext/rtehtmlarea/htmlarea/skins/default/htmlarea.css
[HTMLArea::init]: Editor content skin CSS set to: http://www.jorgo.org/typo3/sysext/rtehtmlarea/htmlarea/skins/default/htmlarea-edited-content.css
[HTMLArea::registerPlugin]: Plugin ContextMenu was successfully registered.
[HTMLArea::registerPlugin]: Plugin DefaultInline was successfully registered.
[HTMLArea::registerPlugin]: Plugin BlockElements was successfully registered.
[HTMLArea::registerPlugin]: Plugin BlockStyle was successfully registered.
[HTMLArea::registerPlugin]: Plugin CharacterMap was successfully registered.
[HTMLArea::registerPlugin]: Plugin TextStyle was successfully registered.
[HTMLArea::registerPlugin]: Plugin TYPO3Image was successfully registered.
[HTMLArea::registerPlugin]: Plugin TYPO3Link was successfully registered.
[HTMLArea::registerPlugin]: Plugin FindReplace was successfully registered.
[HTMLArea::registerPlugin]: Plugin RemoveFormat was successfully registered.
[HTMLArea::registerPlugin]: Plugin TableOperations was successfully registered.
[HTMLArea::registerPlugin]: Plugin AboutEditor was successfully registered.
[HTMLArea::generate]: Toolbar successfully created.
[HTMLArea::generate]: Editor iframe successfully created.
[HTMLArea::initIframe]: Iframe baseURL set to: http://www.jorgo.org/typo3/
[HTMLArea::initIframe]: Skin CSS set to: http://www.jorgo.org/typo3/sysext/rtehtmlarea/htmlarea/skins/default/htmlarea-edited-content.css
[HTMLArea::initIframe]: Override CSS set to: http://www.jorgo.org/typo3temp/rtehtmlarea/defaultPageStyle_ada10bc288b6e2202044.css
[HTMLArea::initIframe]: Content CSS set to: http://www.jorgo.org/typo3/sysext/rtehtmlarea/res/contentcss/default.css
[HTMLArea::initIframe]: Editor iframe head successfully initialized.
[HTMLArea::initIframe]: Failed attempt at loading stylesheets: [Exception... "A parameter or an operation is not supported by the underlying object" code: "15" nsresult: "0x8053000f (NS_ERROR_DOM_INVALID_ACCESS_ERR)" location: "http://www.jorgo.org/typo3temp/rtehtmlarea/htmlarea_6296554ed405001284ee_compressed.js Line: 59"] Retrying...
[HTMLArea::initIframe]: Failed attempt at loading stylesheets: [Exception... "A parameter or an operation is not supported by the underlying object" code: "15" nsresult: "0x8053000f (NS_ERROR_DOM_INVALID_ACCESS_ERR)" location: "http://www.jorgo.org/typo3temp/rtehtmlarea/htmlarea_6296554ed405001284ee_compressed.js Line: 59"] Retrying...
[HTMLArea::initIframe]: Failed attempt at loading stylesheets: [Exception... "A parameter or an operation is not supported by the underlying object" code: "15" nsresult: "0x8053000f (NS_ERROR_DOM_INVALID_ACCESS_ERR)" location: "http://www.jorgo.org/typo3temp/rtehtmlarea/htmlarea_6296554ed405001284ee_compressed.js Line: 59"] Retrying...
[HTMLArea::initIframe]: Stylesheets successfully loaded.
[HTMLArea::initIframe]: Design mode successfully set.
[HTMLArea::initIframe]: All plugins successfully generated.

(issue imported from #M8139)