utf-8 codec error

Hi, have used my CNC all day then set up a new job to cut.... file won't load? Warning at bottom right of the screen says
'utf-8 codec can't decode bytes 0xb0 in position 452: invalid byte.'
Many web pages result in  a search for this error... all explained in programmers gobblygook. Can anyone here tell me what - and where - to fix this
Any reason why is has suddenly appeared?
Annoyed
Thanks

Your file has some corruption or higher order characters in it.

OK.. Well bypassing the programming gobbldygook... only thing different on this file was a new tool - a tapered nose ball end. I went back and changed the tool designation in vectric (the program used to make the file) ((Not the tool name) and re tried the file - seems to be working. I think the utf-8 doesnt like the degree symbol maybe?? Being a tapered ball nose is has the degree symbol (small o) in the tool type description in Aspire. Any comments??
Thanks