Why is the whole captcha form not appearing?

When I try to download from file hosting sites like hotfile, it's prompting me to fill in a captcha code. But my problem is that the whole Captcha form (the captcha picture and the field I'm supposed to type it in) is not appearing. This problem only started occuring during the last 3 or 4 days. Sometimes, I clear all my cookies and then the form appears but most of the time, it doesnt work. What could be the problem? How do I solve it? The problem occurs whether I use firefox or chrome. Please help me.