Short story:)

Short introduction...
For as long I can remember I've loved computers. When I was a child my brother bought first one and I started learning computer programming. For many years I've written a few useful applications. Some of them I sold for relative much money.

Previous year I had some free time so I decided to write an application for dentist's office. Goal of this application was improving management of the patients' data. I was going to write a thin client which could comunicating with database server. It was one of the large applications with very simple construction, so designing, programming and testing took me about one month. When it has been finished I rang to my client up and I arranged meeting. As usual in these situations I've installed my application on laptop the day before and I tested it. Next day I packed my computer and I went to the city where my client lived. When I was going I realized that I've forgotten add "Exit" option to the main menu of application (it is common knowledge that user should be able to close computer application by pressing "Exit" from main menu), unpacked the computer and I've corrected this mistake. When I arrived to destination place I started preparing my computer hardware to present my software to the client. About 2 minutes after I've started my presentation I realized that power led in my laptop had started blinking. I stopped talking and wanted to [podlaczyc zasilanie sieciowe]. I took out one part of my power supply adapter and wanted to take out the second one, but I couldn't do it. There wasn't it. I looked for it twice or tree times. "I've forgotten it" I thought. "Sorry, but I had bad news for you.." - I started talking to my client. His face was getting red. "Give me a ring when everything will be done" - he only said at the end.
On the next meeting I had my and my girlfriend's laptop...
What did this situation learn me? hmmm.. I think I've learned me that I must check everything several times and ...... always give a spare laptop:)