I'm doubt imread() calls a function called Image(). That just doesn't sound right. Why? Well there's a built in function called image() - with a lower case i. So would the Mathworks make a function internal to imread() called Image() - with an upper case i? I doubt it.
I think this is a case of you not copying the actual error message but just typing it in, paraphrasing it, and getting it wrong. Please copy all the red text, and paste it back here so that we have the EXACT error message, which will include line numbers and actual lines of code and actual error messages.
Just to be sure you didn't redefine functions with your own and destroy the built in functions (as Azzi suggested), tell me what these lines of code typed into the command line say:
which -all imread
which -all imshow
If you don't see this:
C:\Program Files\MATLAB\R2012b\toolbox\matlab\imagesci\imread.m
C:\Program Files\MATLAB\R2012b\toolbox\images\imuitools\imshow.m
then you need to rename your programs of the same name that are confusing the interpreter.