iPhone lag when plugging in speaker

[simpsonsay]

Can anyone help me with this problem? and has anyone experienced the same thing?

This has happened twice so far in the past couple of days, and it's starting to concern me. The first instance happened yesterday morning -- around 8AM, I noticed that when I plugged in the speaker cord for my cassete adapater (in the headphone jack) the iPhone would lag to the point where I couldn't do ANYTHING, but once i unplugged the cord, the iphone would not lag anymore. I tried this over many times, I turned off 3G, went into airplane mode, rebooted the iPhone, deleted the last app i installed (IMEEM), and still, whenever the headphone jack was plugged in, the iPhone would lag.

Later on that day--- it worked. So I thought the problem had somehow solved itself.

Low and behold, today, right now, I want to listen to my music at work, I go to plug the portable speaker I have here into the headphone jack, and the iPhone is lagging horribly again!

Anyone know why this is happening? Any help would be greatly appreciated.

some specs on my phone -

iPhone 3G 8GB
iPhone 3.0 OS
AT&T service with the carrier profile where Tethering is enabled (but sadly not MMS)

Thanks in advance.

****EDIT**** just a couple hours later, I plug in the speaker and it WORKS AGAIN. do you guys think its the network causing this? ....