I've had this unit for a little over a year and the problem I'm having is that some DVD's will not play audio, it's hooked up via HDMI to HDMI. As the DVD opening menu comes up, it will play the initial sound that comes up to the menu screen, but when you click "Play" we get no sound.

Most DVD's play fine, but some don't it seems to be a problem with older DVD's, that played fine on our previous DVD player. Has anyone else experienced this?

no one else has had this occur?

Certain models of DVD player or recorder have a poor interpretation of commercial DVD menus and automatic default settings. Admittedly, this is also caused by Hollywood's inconsistent DVD authoring. What happens with some DVDs is your Sony misunderstands which soundtrack its supposed to play "automatically", if you don't choose one yourself. It might default to a 5.1 surround mix that your TV signals it is unable to play thru HDMI, so you get a picture but the sound mutes. Or, the Sony gets confused into thinking there is a commentary soundtrack on the DVD that actually doesn't exist: when it tries to play it, of course there's no sound. The remedy in all cases is to go to the DVD menu and choose a soundtrack that works: "English Dolby 2.0" almost always does.

If that isn't the issue, either your Sony, your TV or the HDMI cable could be faulty. Try another cable, if that doesn't change anything try connecting the Sony to a different TV with a different HDMI cable. If there's still a sound problem, the Sony is defective. The 555 is not exactly known for great build quality, so you might have got a lemon- unlikely, but possible.

re: Sony RDR-VX555 sound problems

I appreciate your reply, to clarify, this does not happen frequently, I'd say it's less than 5% of DVD's we've tried. I didn't try changing the sound mode, it actually runs through a Bose Lifestyle® V20 home theater system, not the TV speakers.
This Sony RDR-VX555 unit also (very annoyingly) will freeze, with brand new out of the box DVD's too, it has done this at times, then it seems to be ok for a while, almost like it can't read the DVD skipping, stuttering.... I'm ready to junk the darn thing, We love our Sony TV but boy, this DVD player has been a pain.

Unfortunately the only decent items Sony makes anymore are the PS3 and TV displays. Everything else is third-rate crap dressed up in the Sony label. The additional symptoms you describe are typical of those reported by owners of the 555, so your sound problem is likely just an offshoot of the machine's overall flakiness. With DVD recorders in steep decline as a product category, there aren't many choices of good ones that work well. I'd suggest a current Panasonic model that ends with "8" like EZ-28- the Panasonics are reliable recorders with decent burners and remarkably good playback thru HDMI. New Panasonics will hit stores shortly, probably with model numbers ending in "9", these should be as good or have slightly improved tuners. If you're on a budget, the Sylvania and Magnavox units at Wal*Mart are remarkably good for the price (way better than the 555). And of course, the Phillips 3576/Magnavox H2160 with both DVD and hard drive recording are the ultimate in convenience/flexibility if you can afford $260 and need ATSC tuning for off-air broadcasts.

Just so you know Panasonic DVDRs (with HDMI, which all current ones have) work quite nicely with Sony displays. You can utilize the HDMI control(if your Sony has that feature) to automatically switch inputs among other things.
Citibear is correct, Sony makes some decent new products but most would agree DVDRs aren't one of them.