Strange Upload Error in 2.5

Okay, I know there are a lot of “Upload error” threads on the forum already, and I’ve read a lot of them. I’ve even read the Upload Error sticky on the page, and following some of those steps, I have managed to get the upload to work, although with some weird kinks.

Here are my issues:

I’ve been uploading pics with 2.5 since it was released and it has been swell. No problems at all. And then last night, out of the blue, I get error messages while the images are crunching:

“HTTP error.” and “An error occurred in the upload. Please try again later.”

So following some steps I read here, I activated the plugin to disable the flash uploader (“No Flash Uploader” plugin), which sorta fixes the problem. The image uploads and stores just fine, creates thumbnails, all that good stuff, but I still get the below message:

“Specified file failed upload test.”

Again, the images upload just fine, and I can use it on the site, but I’m worried about the message, and if possible, I’d really like to use the flash loader, since it’s more convenient and I can select a full gallery instead of doing it one pic at a time.

I’ve contacted my web host and they say nothing was done to my server, so the issue isn’t on their end. Plus, I’ve followed all the recommendations to add lines of code to the htaccess with no success.

Any thoughts, anyone?