problem with avast 5

i have installed avast to replace my previous av program and when i ran a scan a great majority of my files could not be read and it gave an error next to it 1 said "the system cannot read from the specified device(30)" on a file off my c drive

the rest all read
"the file cannot be accessed by the system(1920)"

or

"system cannot find specified file path(3)"

all of these are from the f drive which is my secondary hard drive not counting my backup partition