My wife's HP printer exhibits a rather strange problem: frequently (but not always) the printer will print a page of text that contains 'bands' of light (and poorly printed) text. Each band consists of about 5 lines of similarly light/poor text. So a page will have about 5 lines of nice clear dark text followed by 5 lines of light/poor text, then another 5 lines of good text, etc. etc.

This doesn't happen with every text page and we have already changed black ink cartridges, performed the cleaning function and the alignment funciton.

Anybody else experienced this type of problem or have suggestions for fixing it?