When I try to upload a file to my gmail using firefox or safari, the navigators gets me an error or gets closed

I bought a Macbook Pro 7 months ago. In general everything works properly until yesterday.

Since yesterday, I can send attached files with my gmail because when I try to upload a file with my gmail account Safari and Firefox gives me an error and automatically, the navigators gets close.

At the beginning the navigators gives me a flash player error, but yesterday when I saw that error, I uninstalled the flash player and when I tried to upload a file, the navigators gets closed again. I downloaded and intalled again the new flash player for mac but the error begins.

I don't know how to fix my problem, can somebody help me?