Cannot log into bank account

[Phil]

This might sound like a pretty lame question, but I'll ask it anyway

I cannot log into my bank account on this computer running Mint 17.3, 
all I'm presented with is a blank screen after entering my account name 
and password. It's not a bank problem because I can login on another 
Ubuntu based system (14.10) without any problems.

Can anyone offer a cure or a suggestion where I might look for a cure? I 
should add that I've not had this problem before today.

A Google search for the same problem indicated that a virus was the 
cause in a Windows system. I may have updated Firefox since the last 
successful login, I can't remember.

-- 
Regards,
Phil