Validation Rules Fading

I am working on a spreadsheet with data validation in place for some columns. However, the yellow validation input message fades and becomes illegible after a few minutes of work on the spreadsheet (font turns from black to white). When I close it and reopen it after this happens, an error occurs and the spreadsheet fails to open until I try a second time and the spreadsheet opens with the input message restored until it fades and the problem starts again. Does anyone know what the cause of this problem might be? The validation rules were all done on about 50 columns using the list option with a series of highlighted values providing an exhaustive range of what is allowed to be entered in a given column. Do these types of problems arise when too many list validations are used? If so, does anyone have any links explaining alternate ways of customizing validation rules using a custom formula? All of these rules have to restrict columns to a range of whole numbers, but also allow for our missing data code of 99, which falls outside the range.

Thank you for your help.

Doesn't sound like a Data Validation problem sounds more like Conditional Formatting has been set somewhere.

Fading font sounds like something out of a mystery movie with fading ink! LOL