hello, can you try to replicate this behaviour when you launch firefox in safe mode once? if not then maybe an extension is interfering...

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

tried all the things you suggested...still no luck

i also found out that other browser cant access blogspot.com, so probably isnt firefox but is my laptop. Other computer in the same network is able to access it...

I have scan anti virus and spyware but nothing seem to work. Any suggestion on how to proceed?? Thanks

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

thanks for the answer...while your suggestion doesnt work, i am able to access to the website after repeatedly scan for virus and restart my computer several times in one day.

It may not be a long term solution as i still did not know what is the cause of the problem, it will do for now.

thank you all for your time