Reader is producing grey pages - cannot read

Yesterday my scanner (Canon) produced grey pages rather than readable files.

I assumed the scanner was at fault.

Have connected my husband's scanner (HP) and this will scan ok. but in JPEG format

However when I try to open most PDF files from my PC they are opening as grey pages - nothing there.

I tried to combine the jpeg files to a PDF which is normally fine but although I could see the jpegs ok - the combined file was grey again.

But some PDFs on my desktop are opening ok.

I tried an update on Adobe but it said none available.

Any ideas?

Thanks

Message was edited by: Helen Evans