This article covers bugs and limitations of the widely used application Photoshop and hopefully their workarounds. Some problems are system specific (different flavours of Mac OS and Windows), some are found in a certain program version (like Photoshop Elements, 7.x, 8.x aka CS or 9.x aka CS2) or file type specific (e.g. 16 bit TIFF files with alpha masks). Some of the workarounds might advise to use a different application for a certain task.
Resizing introduces a visible seam line
This is a common Photoshop problem on both platforms. It only happens when a file is not reduced to the background layer (or flattend) prior to resizing. Before flattening make sure you have saved a copy of your layers file (normally a PSD or PSB) when you think you might need those layers again.