W7 Upload issue with Wordpress

[crankybyeatch]

Hi, all. I have a really weird problem that is baffling everyone I ask so here goes.
I have W7 Home Premium on my desktop system. I also have a laptop with WXP.
I maintain a blog and web site for my non-profit group on Wordpress.
The blog is on the wordpress.com platform, the web site on the wordpress.ORG platform.
From my desktop I CANNOT upload files larger than about 400kb to the .ORG site but I can from the laptop.
I CANNOT upload files larger than about 400kb to the .com site from the desktop either.
I CAN upload these large files to both from my laptop.
On the desktop, It doesn't matter which browser I use, IE or Chrome.
I am not a computer guru, just an average user but am desperate to find a solution to this as my laptop is not going to last forever and I will be relying on my desktop.
As mentioned, Wordpress don't know where the problem is, my web support guy doesn't and the techs at the place I bought the desktop don't know.
I'm at my wit's end. Can anyone help? Thank you!
Loni

 

[Core]

400 kb is a really small size for a file, less than half a megabyte.

Please define "cannot upload". Are you using a web interface, or ftp? Do you get an error message, or does it pretend to upload yet doesn't?

We need more information...

 

[TrainableMan]

Maybe try THIS tweak to your theme functions file?

It could also be a limitation on the host server as well, in which case it has to be altered there. See THIS (2 years old) and THIS (3 years old) to see if they offer more insight?

 

[crankybyeatch]

Thank you, everyone, for your suggestions. The problem does not appear to be on Wordpress' side as I have a generous upload size available. I can upload large files to the site using my laptop which is Windows XP, just unable to do same on desktop which is W7 Home Premium.
I use the upload media page on Wordpress.
I don't get an error. WP appears to start the upload and then stops. It never gets to complete it.
I'm not a systems expert so I can't answer tech questions. Sorry!

 

[Core]

This is certainly a baffling one...so let's start with the very basics.

Have you installed all the available patches from Windows Update?

Have you run a scan for malware on your system?

Have you tried updating the network driver for your computer?