here is the code i am using

1. <form name="uploader" method="POST" target="hidden_form" enctype="multipart/form-data">
2. <input type="hidden" name="MAX_FILE_SIZE" value="1000000">
3. <input type="file" name="upload_file">
4. <input name="submit" type="submit" value="Upload">
</form>
5. <iframe name="hidden_form" src="upload.php" height="0" width="0"></iframe>

try to use code what i have posted just above your post,
i think you need to give action on form, remove src from iframe.

the src for the iframe is the php page that resizes and renames the uploaded images. all uploaded images need to be passed through this page so they have the correct dimensions for the next section of the site.

i have changed the code so i now have an action="upload.php" and left the src as " ".

i will upload the files to the server.

the page still reloaded on me. does the action="upload.php" sent the from to the upload page or does the iframe stop this from happening.

i have solved this problem with thanks to the pointers from dangerdev. to fix the problem i took the form off the page where the user was being asked to upload the image and put it on to the upload.php page.

i then just created an iframe with dimensions added to it and said set the src to upload.php. as the submit button was on this page and was activated within the iframe it stops the page the user is on being reloaded thus stopping the entered information being lost. the code i used for the iframe is here.

<iframe name="uploadframe" src="upload.php" width="400" height="150" frameborder="0"></iframe>

this now just looks like it is part of the page it is on and the user would be none the wiser iframes are being used.