Blank cells on one PC

[SteveMcCulloch]

We have a PC which since the weekend will not view a number of files correctly. The files appear to be ones with small text fonts / zoomed out. The files open okay on all other PC's but on the problematic PC the worksheet is blank. In some cases the cells are just one large coloured block and in all cases if you format cells and resize the font, or you zoom in the cells become visible.

I have seen a similar post which was responded with suggestions of custom cell formats, however there were no odd cell format types.

Any ideas?