Help! - Image Uploading Issues with Safari & FF from my Mac at Home

Hello All...I have been having this issue for quite a while now (since one of my latest Java, Safari updates) I am running 10.5.8 and can upload images to fb, flickr and any other site without a problem except to one in particular, where my official website is at. To that site, I canot upload anything from either Safari or FF...however, when I am connected with my MacBook Pro from work, I am able to upload images without a problem. My questions are:

1- Of course, why can't I no longer use Safari or FF to upload to that ONE website from home any more while I still can do it to any other site like fb, flickr, etc...?

2- I have run the same updates for my MacBookPro, and I can't use it to upload images to that ONE site from home, but from my work network it works just fine.

3- Is it a nrework issue? It looks like, but...should that give me troubles as I upload images to other sites? Again, I can easily upload from home to any site except that ONE in particular...

Please, help...Thank you!