capture file appears to be damaged or corrupt

Did you capture the packets on the same system as where you are trying to view them in Wireshark? If not, how did you transfer the file from the capturing system to the Wireshark PC?

Most times I have seen this message, the files were transferred by FTP, but in ASCII mode instead of BINARY mode. This will mangle the file (as different systems use different line endings and FTP in ASCII mode tries to change byte sequences that look like line-endings).

So if you did transfer the file with FTP, please enable BINARY mode before sending the file over.

It seems like you might have a version of libpcap (winpcap) that has been modified. You should not see captured packets longer than 65535 bytes. Try reinstalling winpcap.

Alternatively, if you have an intentionally modified version of winpcap (perhaps one that supports larger packets), you'll need to adjust the following:

wiretap/libpcap.c, lines 756-771:

if (hdr->hdr.incl_len > WTAP_MAX_PACKET_SIZE) {
    /*
     * Probably a corrupt capture file; return an error,
     * so that our caller doesn't blow up trying to allocate
     * space for an immensely-large packet, and so that
     * the code to try to guess what type of libpcap file
     * this is can tell when it's not the type we're guessing
     * it is.
     */
    *err = WTAP_ERR_BAD_FILE;
    if (err_info != NULL) {
        *err_info = g_strdup_printf("pcap: File has %u-byte packet, bigger than maximum of %u",
            hdr->hdr.incl_len, WTAP_MAX_PACKET_SIZE);
    }
    return -1;
}

and wiretap/wtap.h lines 308-313:

/*
 * Maximum packet size we'll support.
 * 65535 is the largest snapshot length that libpcap supports, so we
 * use that.
 */
#define WTAP_MAX_PACKET_SIZE            65535

Updating to the latest version 1.12 (at the moment) resolved the issue for me