Most of the ai files I receive show to be compressed and I cannot do anything with them. I think I should be able to open them with CD X4, which is installed alone and also in a bundle with my Wilcom digitizing program. Someone indicated that the two installations on one computer could cause problems, but it is convenient having both redily available.
AI files are often actually PDF files with an AI extension. So, you could try renaming as .pdf and see if it opens in a PDF reader. If it does, try importing into X4.