I wrote to my student the other day:

下周的课改在一点上怎么样？

He replied: 

好吧，没问题。

I was pretty sure he wanted to say "Ok, no problem." However, the "好吧" made me feel a little confusing: was that hard for him to accept the new schedule?

For all beginners, we know '好的' means OK as response. It simply shows you are agree with what other people suggest, or you get the information from other people Like:

─ 明天 五点 见。

─ 好的，不见不散。

or:

─  调查报告 下午 交给 主任。

─ 好的，我 已经 差不多 写完了，只要 再 做 些 修改 就好了。

or: 

─ 这里 要 用 红色，还有，那个 地方 的 字体 太大了。

─ 好的，我 记下了。

It is a rare usage for 的 here, for most of time we say 我的、好的、冷的、漂亮的 to describe or define something. For example:

 我的好朋友、好的设计、冷的咖啡、漂亮的鞋子

We never or very seldom answer someone else with  我的 as the universal reply for any agreement.

On the other hand, 吧 can be used with 好 as kind of answer. Like: 

─ 你 下个月 跟 小王 一起 去 北京 开这个会，怎么样？

─ 只有 我们 两个？

─ 是的。

─ 恩，好吧，但是 我们 能不能 在走之前 跟设计师们 先 开个会？

……

or:

─ 这学期 你 教 A班 和 B班。

─ B班 可能 不行，我 下午 都 没有 时间。

─ 好吧，你 教 A班，B班 让 别的 老师 教。

It is more reluctant to answer with 好吧 than 好的. As the examples we see above, when people think they can not accept without problem, they use 好吧 as a sign of "Well, I will do it, but you know..." It's common to declare the problem either before or after 好吧 sentence.

That's why I was very confused when I saw the reply from my student: 好吧，没问题。Either he wanted to say he has some trouble to change the schedule or he had no problem. After further question, I knew he meant 好的。