Issues with seeing all of the filter options?

Hi,

Not sure if it is just my computer, but recently I have been unable to see the bottom section of filter options.

Its all fine for the filters with less than about 10 options, but anymore and I just cant see them??

I am using the latest version of FF - have been using the program for about a year so only a recent development.

Not sure if these screen shots help but this is my issue - all looks fine here:



then i try to scroll down to the rest of the options and see this



the rest of the options are just not accessable anymore?

Any help appreciated.

Thanks
Sara