TAKOBOTO

right in the middle of
Right in the middle of the ceremony, the lights went out.

かんがえているさいちゅうに、はなしかけられてこまった。

right in the middle of thinking, someone started talking to me.

のゲームをやっているさいちゅうにがきどうされるのをぼうしします。

(Screen saver -> Off) Prevent the screen saver starting up in the middle of playing the game.

ふゆのまっさいちゅうのとざんはじゅうぶんなふゆやまのけいけんがなかったらやめるべきです。

You should stay away from mountain climbing in the midst of winter unless you have ample experience in mountais in the winter .

しょくじをしているさいちゅうにじしんがおきて、おおさわぎになった。

Right in the middle of a meal, an earthquake occured, and there was a giant uproar.

かれのえんぜつのさいちゅうにちゅうざする。

Leave in the middle of his speech

かのじょはしょくじのあとかたづけのさいちゅうだった。

She was in the middle of washing up.

Just as~ is happening. Express that something stops another thing already in progress.

DinhNhat

This word can also be pronounced "sanaka", and has appeared in that form in several JLPT 1 guidebooks.

your name

Happens to me all the time since I got a game controller - it doesn't count as 'activity' as far as the OS is concerned ;_;.

Amatuka

theres also 真っ最中, meaning in the midst of, e.g.
受験の真っ最中 - in the midst of taking a test.

Snake

When we say 受験の真っ最中 it means being in the exam season. ex 受験の真っ最中ですが、気分転換にディズニー・シーに遊びに行きました。in the midst of taking a test would be just '受験中に' or '試験中に'. 受験 might be special.

Miki

As compared with 真っ最中（まっさいちゅう）、真っ直中（まっただなか）I think has more of an urgency or reality.

bamboo4

ah ok thanks, I thought there may have been that sort of nuance to it (saw it in GTO ^^)

Snake

What the hell is GTO?

bamboo4

Great Teacher Onizuka

Miki

Okay, you compelled me to ask. Who is GTO?

bamboo4

This やつ!

dc

I see, thanks! You guys float in a dimension that is completely alien to me. But, its alright, I don't wanna know.

bamboo4

Is this similar to 途中？、してる間？

nazonatte69

hmm Pls do not includ me in the guys. 私は、おたくじゃない！There was TV drama, GTO, starred by Sorimachi and Fujiwara Norika.

Miki