Excel copy and paste malfunctioning

Since a few days ago My copy/paste function does not work so well in Excel. If I copy from VT into Excel, everything goes into one column; if I try to copy a row into several rows below (eg A1:C1 into A2:C10), it tells me the copy and past ranges are different sizes but lets me copy the values into one row (A2:C2).

I can sometimes get round the problem (eg for copying from VT) by copying into Word, converting to a table, and then copying into Excel, but obviously this doesn't help where I want to copy formulae.

I don't think I have installed anything new recently, except a VT upgrade, (although I could be wrong).

Any ideas what could be causing it and how I could cure it?