Photos won't upload

Please help. I see that many have posted on this topic before and many of the questions are unresolved.

I cannot consistently upload pics to my blog. I have no trouble uploading to the gallery from my computer or a url but when I try to insert them into the post, nothing happens. I get a blank screen. I have tried with different browsers but the problem persists. I have tried on different computers – to no avail. On occasion, my husband’s pc is more successful at uploading pics than my mac, but other family members’ computers, both pc and mac, are sporadic, like mine. It seems as if my computer is not communicating with WP. I just don’ get it. It’s frustrating. I even bought a new computer with the hope that this issue would be resolved with a new mac. But no. The problem persists. I am frustrated and would appreciate any help. I’ve tried in both html and visual views. I’ve tried different browsers. I’ve tried downsizing the photos. Nothing works. This also happens, by the way, when I try to add links. Sometimes my program takes them and sometimes it doesn’t. Why is this happening? I’ve even tried to change templates, but that didn’t matter either. Help, please!