php redirect through htaccess causing images to be saved as .bmp, why?

[TSx]

I need a little insight on a problem that I'm experiencing on my site. This is an Internet Explorer only problem that is affecting many of the users on the site. I sort of know why this is happening, but I have yet to think of a way to resolve the issue.

Below are two links that our site uses:
http://www.imagelink.org/id7218.jpg
and
http://www.imagelink.org/?id=7218

The first link does NOT work as intended, giving IE users the option to save as a BMP only. This is the redirected link that our site uses to send the user to the second link, which works just fine when clicked. We used this method to avoid dealing with forums that do not allow dynamic images. It seems that the headers aren't passing through on redirect, however, and we cannot find a way to have the first link save as anything other than untitled.bmp.

Does anyone have any idea what could be a possible cause of this? Or have any idea for a solution? As I said before, only some images do it, and it's only in IE, so it's very frustrating.

Below is the code used in our .htaccess file, I don't know much about htaccess so the coding may be archaic, and if there's a problem in it, please let me know:

Options +FollowSymlinks
RewriteEngine on
RewriteCond %{REQUEST_URI} ^/id(.*?).jpg$ [NC]
RewriteRule (.jpg)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).gif$ [NC]
RewriteRule (.gif)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).png$ [NC]
RewriteRule (.png)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).bmp$ [NC]
RewriteRule (.bmp)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).psd$ [NC]
RewriteRule (.psd)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).swf$ [NC]
RewriteRule (.swf)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).tga$ [NC]
RewriteRule (.tga)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/id(.*?).tif$ [NC]
RewriteRule (.tif)$

http://www\.imagelink\.org/\?id=%1&refer=%{HTTP_REFERER} [R,L]
RewriteCond %{REQUEST_URI} ^/imageid=(.*?)$ [NC]
RewriteRule (1|2|3|4|5|6|7|8|9|0)$

http://www\.imagelink\.org/\?imageid=%1&refer=%{HTTP_REFERER} [R,L]


Thanks in advance for any help/suggestions.

 

[VirtualLarry]

I'm not a webmaster-guru, but the first thing that came to my mind was, what is the MIME-type being sent to the client, for the above-mentioned .jpg file?