You did not tell us
which operating system and version or which video editor or application you are attempting to use for importing the video. You are dealing with 3 different camcorders and (potentially) video formats.
Your DCR-TRV130 is a Digital8, DV format, standard definition video capture, camcorder. MovieMaker, iMovie and most video editors can deal with this.
Your Canon HV30 is a miniDV tape based, HDV format, high definition video capture, camcorder. It can capture standard definition DV format video, but you need to select that option in the camcorder's menu. Most video editors can deal with HDV format importing, but many of the low end or bundled (in the Windows world) cannot. iMovie can.
Your Panasonic AG-HVX200 default capture is DVCPro HD format, high definition video, to the P2 card. It can capture standard definition DVCPro format or DV format to the P2 card and can capture standard definition DV format to miniDV tape. Most video editors at the low end cannot deal with DVCPro or DVCPro HD format. Sony Vegas and Final Cut, among others at the higher end, can.
Since the computer and the TRV130 get along, we can pretty much discount the computer's firewire port and the firewire cable as the culprits. It is possible that the camcorder side of the firewire cable may be an issue as pointed out by Terfyn. That leaves the computer, operating system, video editor or importing application on one side of the equation and the HV30 and HVX200 firewire ports and camcorder settings on the other side of the equation...
And the suggestion to power down the camcorder before plugging in or unplugging the firewire cable to the camcorder's DV port is spot on.