Internet Explorer (Windows), has numerous issues which prevent it from correctly rendering PNG images:

* 4.0 crashes on large PNG chunks. 
* 4.0 does not include the functionality to view .png files, but there is a registry fix. 
* 5.0 and 5.01 has broken OBJECT support. 
* 5.01 prints palette images with black (or dark gray) backgrounds under Windows 98, sometimes with radically altered colors. 
* 6.0 fails to display PNG images of 4097 or 4098 bytes in size. 
* 6.0 cannot open a PNG file that contains one or more zero-length IDAT chunks. 
* 6.0 sometimes completely loses ability to display PNGs, but there are various fixes. 
* 6.0 and below has broken alpha-channel transparency support (will display the default background color instead). 

These issues create problems with display.

* Background images cannot be positioned or repeated 
* Delayed loading and resource use 
* Grey, white, black backgrounds often appear on images 
* Links become unclickable, forms unfocusable