Altitude

My Observer has begun acting strangely with regard to altitude and baro pressure.
If for example I set the altitude at 600ft, my present altitude, without me changing my location, it begins to ascend by itself. By the end of the day I’ve put on 400-500 ft.
The same holds true for Baro pressure. It ascends but not in line with the current pressure.

Does anyone have any reason for this?
I am taking off for a trip on Sunday with some climbing involved and would greatly appreciate a quick response as I would love to have this problem solved prior to leaving.

Thanks,
kwr

	Suunto Observer - Click for more info The shock-resistant Suunto Observer is a tool built for outdoor challenges, but its timeless design makes it wearable in any situation. The Observer is 1/3 smaller in both diameter and width than the first generation Suunto Watches (Vector, Altimax, etc). It also features a chronograph, which previously was only offered in the Navitech but is now discontinued.

[Brad]

When staying in the same location one should preset elevation then lock
the baro in use mode. That way elevation does not move with the
rising/falling barometer.

The baro is changing and effecting the altitude. The units do not
understand location only air pressure. When hiking one needs to update
the altimeter with a topo to offset for barometer changes during the
day.

[Krak]

Brad,
Thanks for replying, unfortunately I was gone when you replied.

I'm a little confused because it was my understanding that when you were in Alt. mode, baro was locked and vice versa so as not to influence each other. This is contrary to your response, if I understand you correctly

If that is not the case how does one "lock it" as you suggest?

The other weird thing that I was finding on my trip was that when I was manually adjusting my altitude either up or down, at a certain point the abreviation "def" would appear where the numerical readout would normaly be
and stop either going up or down. I would press either quick or on off again and the altitude setting would resume moving in the direction I was setting it.

What does "def" indicate when setting the altitude??

Thanks in advance!!
krak