What file format? Does it freeze on the timeline or just upon export?
Share a file with the issue and someone here will check it out. Just upload the file/s to a free server, such as Google Drive or MS OneDrive, get a shared (public) link, copy the link and paste it here or to me in a Private Message via the mail envelope in the top-right corner of this forum.
Using Google Drive, if necessary change "restricted" to "anyone with link can view."