Crash signature - nsStyleSet AddImportantRules
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Crash signatures ( what's this? ): nsStyleSet::AddImportantRules(nsRuleNode*, nsRuleNode*)
This crash can have several causes:
- Extensions: Especially Ask Toolbar and My Web Search Toolbar. If you use one of these extensions, try disabling it. For instructions, see Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems.
- Malicious software: (i.e. malware) To find out if your problem is caused by malicious software, see Troubleshoot Firefox issues caused by malware.
- Firefox bug: In some cases, this is caused by a bug in Firefox. This bug that will be fixed in the upcoming Firefox 3.5.3 release.

Firefox