Odd spaces substituted in log entries

[Sunshyn]

I've been lurking here for awhile, but this is my first post. I've picked up a huge and varied amount of useful information here already. It's an excellent resource. :-)

I've been puzzling over some strange log entries for a number of months now but haven't been able to come up with any correlation between the occurrences. I was hoping someone here might be able to tell me why it was happening.

At least a couple times a week, I see entries for users where a folder name will either partially or entirely be substituted with spaces. They show as spaces in the error log and %20's in the access log. The result is that instead of "/Thumbnails/image.jpg" the entry comes up "/%20%20%20%20%20%20%20%20%20s/image.jpg". I'm pretty sure that the number of spaces always matches up with the number of missing letters.

The user gets broken thumbnail images on any page they go to, and I get these odd entries in my logs. Has anyone else had this problem?

[sugarkane]

Welcome to WebmasterWorld Sunshyn

I'm really not sure what could cause that kind of thing, but I can have a couple of shots in the dark... Are the pages where the errors occur plain html or dynamically generated? Is there any possibility thses entries could be caused by someone else (wrongly) linking to your images?

[rogerd]

Welcome, Sunshyn! Is there any referrer info on these requests? That may help you determine whether the references are internal or external as sugarkane suggests.

[edit_g]

Shot in the dark: they could be from an image search engine. I've seen %%'s coming up in some image engines and in some cases obscuring parts of the original URL - could that be it?

[Sunshyn]

They look like regular browsers, coming through perfectly normal searches (google or google partners, but that could be because that's most of my visitors). They usually don't stay through other pages. I probably wouldn't either, coming upon a page with all broken thumbnails. However, when they do go to a number of pages, it happens every time they come to a page with images from that folder. Everything else seems to be displayed like it's supposed to.

Those thumbnails are generated with PHP (different code from page type to page type). However, I have the thumbnail folder name right in the code while it's the image names are generated from the database. You'd think, if anything, the image names would be the part screwed up, but it's always just this folder name. It happens to occasional people (not robots) with varied browsers, all of which work fine 99+% of the time and all with varied and perfectly normal IP addresses. The rest of the code seems to display perfectly normal. Here's the browsers it happened to in the last week and a half:

Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Mozilla/4.0 (compatible; MSIE 5.5; Windows 98; Win 9x 4.90)
Mozilla/5.0 (Windows; U; Win98; en-US; rv:1.0.1) Gecko/20020823 Netscape/7.0
Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705)
Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)

It's terribly confusing and frustrating because I can't reproduce it, and I can't find any other abnoralities or common threads.