If you're still having problems it's most probably an add-on or toolbar you've installed alongside other software. When installing software (especially any freeware stuff) you'll find multiple confirmation boxes while installing which ask for permission, you have to read each one carefully before proceeding and refuse any toolbars in particular.
If on Chrome then these pages may help :-
https://support.google.com/chrome/answer/113907?hl=en-GB,
http://www.howtogeek.com/140464/how-to-manually-uninstall-a-globally-installed-chrome-extension/ &
https://support.google.com/chrome/answer/142064?hl=en-GB
If you paste
chrome://plugins/ or
chrome://extensions/ in to a new tab they'll take you directly to the required page and you may need to use the Windows uninstaller in Control Panel as well.
BTW the
chrome://plugins/ page is useful if you have a lot of Flash plugin crashes as Chrome can have access to both its own Flash plugin and the System version. Just disable the plugin one and you'll never have another problem again.
This is mine, the one in red is disabled :-
Adobe Flash Player (2 files) - Version: 11,8,800,94
Shockwave Flash 11.8 r800
Name: Shockwave Flash
Description: Shockwave Flash 11.8 r800
Version: 11.8.800.97
Location: C:\Users\Colin\AppData\Local\Google\Chrome\Application\29.0.1547.66\PepperFlash\pepflashplayer.dll
Type: PPAPI (out-of-process)
Enable
MIME types:
MIME type Description File extensions
application/x-shockwave-flash Shockwave Flash
.swf
application/futuresplash FutureSplash Player
.spl
Name: Shockwave Flash
Description: Shockwave Flash 11.8 r800
Version: 11,8,800,94
Location: C:\Windows\system32\Macromed\Flash\NPSWF32_11_8_800_94.dll
Type: NPAPI
Disable
MIME types:
MIME type Description File extensions
application/x-shockwave-flash Adobe Flash movie
.swf
application/futuresplash FutureSplash movie
.spl
Disable Always allowed?
Do run a FULL virus scan with MSE or the free Malwarebytes' Anti-Malware( or any good scanner that searches for malware as well as viruses) after you've finished. Download and run the free version of ccleaner(short for crap cleaner :) )
http://www.piriform.com/ccleaner/download and clean your registry as well.