ok good idea i hope will get a better result.
As Sted says check it first, if not:
If you are using a splitter you may need male to female for the main connection (PC to splitter)
These are decent cables, if you want a bog standard cheap one:
thanks alot i really appreciate your support.
I've had this with a whole batch of PC's, none connected to VGA splitters, they were obviously just supplied with terrible quality VGA leads. Changing for any other cable solves the problem
Does the colour on the IWB look more clear when you changed the VGA cable?
Change your VGA Cable. the cable that comes for monitor and goes to your CPU. The blue coloured adapter. the smudges will vanish.
As other people have said simply test with another VGA cable from another classroom that you know is fine to see if its the VGA cable.