Hi begee and welcome to the forum,

I first thought daylight saving time might have got you but if you can still get the problem that isn't it.

VBA macros simply send stuff to the machine and if you are doing other stuff, like opening files or the such, the macro sends it to the wrong program. I suggest you try using some DoEvents in your code to let the OS do what it needs to do and keeps the macro running on your Excel program instead of others.

http://vbcoderesources.blogspot.com/...ts-in-vba.html